A few questions

The low idle could be the idle air control or dirty throttle body. But it looks like you got a car where the oil was not changed regularly nor the transmission serviced. So you are looking at a potential bad engine and a slipping transmission will not last long. It might be the best to just look at trying to mitigate your loss with another car.

What exactly are the codes? The numbers, not some interpretation. When you get the codes read at AutoZone, they give you a cash register printout of the code and its “meaning”. The code will be at the top. Post the actual code(s) here, I/we don’t care about their “meaning”.

Let’s back up a bit.
You need to have a mechanic do a thorough evaluation. Reading the fault codes will be part of that, and I’ll second Keith’s request to have you post them here. Shop time in most areas sis about $100/hr, and depending on the shop it’ll cost you between $100 and 4200. Then you’ll have a list of what’s actually going on.

When you bought the car you had known problems. A (coolant?) leak, fault codes stored, a possibly bad transmission, and a possibly bad catalytic converter. And now, when the engine is idling or at full operating temperature ("after driving a good 5-10 minutes), your oil pressure is low and the engine sputters and stops operating.

I’m going to be honest. Don’t be surprised if the shop tells you that the car was neglected and possibly abused and is pretty much shot. By that I mean that the compression will probably be very low and uneven between cylinders, the transmission is bad, and the cost to repair it will be far more than the vehicle is worth.

I’m also going to go out on a limb and suggest that the reason the lady called a few times to see how the car was doing was out of guilt…she knew the car was shot. But she did not scam you. Buying a used car is truly “let the buyer beware”. It was your responsibility to determine the condition of the vehicle before purchase, not her responsibility to tell you.

Let us know what the mechanic finds. If I’m wrong, I owe you lunch.

I had the car checked and the mechanic told me that I need to replace the following:

Idle Air Control Valve
E.G.R. Valve
Intake MainFold Gasket (Upper & Lower)
Feul Injector

None of these are going to address your slipping transmission, and unless he did an oil pressure reading he has no idea if the oil light was due to a worn engine, fuel contamination; bad or clogged oil pump, or a idle speed that is dropping too low. Have you at least checked the dipstick to see if it is low on oil?

I’d like to help you but I need those codes first.

IMHO there is no reason to get the engine running properly w/o knowing whether or not there is an oil pressure problem, and not knowing if the trans is shot. Just the trans could be more than the car is worth. A standard equipped Cougar in fair condition is about $850 and in excellent condition about $1400.

Codes:
PO430
PO171
PO174
PO1744

That list your mechanic gave you sounds like he’s taking out the scattergun and not actually doing any investigation. So are you sure you were told that they all needed to be replaced? Or that those are potential causes?

Leaving aside the P1744 for minute you very well MIGHT need some work on either the EGR system, the intake manifold, fuel injectors OR the IAC (unlikely). With the P0171 and P0174 it seems quite likely that you are running lean and this goes with your symptoms. “Running lean” means too much air (intake manifold, IAC, EGR - sort of) or not enough fuel (fuel injectors - or fuel pump. Was the fuel pressure checked?). I’m guessing that you have a vacuum leak and one needs to find out where the leak is - for sure - not by guessing.

IF it comes down to any work on the EGR - it IS a system and not a part. Yours likely has three main parts - a flow sensor (DPFE sensor); a vacuum solenoid; and the valve itself. In addition there are vacuum lines connecting all of those parts together that have to be checked.

If all of this is Greek to you then you need to find someone who a) knows what s/he is doing and b) is willing to do some diagnosis rather than just guessing on your dime.

Until the P0171 and P0174 are sorted out I would ignore the P0430. The former codes come from the upstream (before the cat) O2 sensors. The latter comes from comparing the upstream O2 to the downstream (after the cat). If the upstream sensors are reporting a problem then there’s no point in chasing a code that could just be derivative of that.

The P1744 is completely unrelated to the others and it means your torque converter clutch is stuck off (or reportedly so). Has this transmission even been serviced? Pan dropped and filter changed? Do it. You might get lucky. Don’t do a lot of highway driving as that might overheat your transmission.

To answer your first question, the mechanic told me there were 4 leaks… and I’ve listed those.
I’ve never has the trans serviced because I only had it for 3 months. And I don’t know about any previous service on it.

I didn’t see a report of verified leaks. So are you saying that the mechanic verified that all of the following are leaking:

  • both intake manifold gaskets
  • EGR valve (where - there are different spots)
  • IAC valve
  • one or more fuel injectors

Is that what you mean by the 4 leaks you listed? If those are all verified, then all of that would need to be done and would cause the P0171 and P0174. It will cause the engine to idle poorly (but do ok under acceleration), and if the idle drops low enough send the oil pressure too low.

@cigroller

Yes, he said they are all leaking. And the description in your last paragraph sounds like what I’m going through.

I don’t find the “story” that the mechanic verified these leaks to be all that plausible. Here are some reasons.

First, the list looks a little like something you’d get if you just did an internet search for rough idle and P0171 / P0174. And the list would say “possible causes”

Second, if you had fuel injectors leaking on the outside it would probably give you problems all of the time rather than just at idle. You should also be able to catch of whiff of raw gasoline under the hood at least some of the time (do you?) (If the injectors were leaking inside that would mean fuel and you’d get codes for running RICH not lean)

Third, the EGR system itself is monitored. They can easily have problems without themselves throwing codes, but for now there don’t seem to be any error codes for the EGR system so I would drop that. Aside from that what the EGR does is pump some exhaust gas into the intake. In terms of symptoms it can act like a vacuum leak, but it’s not likely to produce a lean code. There are reasons that it can lead to actual vacuum leaks, but I’m not betting on it as it isn’t a typical failure mode for the EGR system.

Fourth, the P0171 and P0174 each refer to two different sides of your engine. (“Bank 1” and “Bank 2,” respectively). If both of these codes appear then I would not suspect intake manifold leaks at first since it would mean both sides are leaking. Of course, they’re probably both the same age and you don’t know the history of the car, so you don’t know how long the engine light has been on and various issues ignored. So its possible that both are leaking. But in general having a lean condition on both banks sends one upstream of the manifolds.

How mechanically inclined are you and how willing to get your hands dirty? You went as far as shooting carb cleaner around. I think it would be worth it to pull off your throttle body and IAC valve and give them a good cleaning and fresh pair of gaskets. This is cheap and easy and good maintenance even if it doesn’t help. It you’re up for it, there are probably about 100 Youtube videos on doing it - maybe not for a 2000 Cougar, specifically, but the basics are pretty generic across different vehicles and you can ask for tips here.

I would also take another poke around for the source of vacuum leaks. (Verifying the existence of one with a vacuum gauge is a fine idea, but given your symptoms and codes I don’t doubt much that you have one). My favorite method is actually an unlit propane or butane torch with a hose rigged to the end - no mess, easy to fish around in various nooks and crannies and around corners.

A dirty Mass air flow sensor can cause a lean condition on both banks. Try cleaning the mass air flow sensor before you replace any of those parts.

I’m a little late to the party here, and I haven’t read all the previous posts in detail–just skimmed through them. But here’s my opinion:
Have the oil pressure mechanically tested. That means a shop will install their own manual pressure gauge, warm the engine up to operating temperature, and test the oil pressure and compare it to the specifications in the Ford service manual. If the oil pressure is lower than the spec, stop right there. The engine is worn or damaged, and any repairs will likely cost well over the value of the car. Not to mention that correcting low oil pressure will not address any of the other issues you seem to have with the car.

The engine in this car is unique to the Cougar and the Ford Contour and Mercury Mystique, cars not known for their easy serviceability and long-term reliability. The codes pertaining to fuel system lean could be caused by a faulty Mass Air Flow sensor, or by vacuum leaks. If I remember, these engines used grommet insulators around the bolts for the intake, so the leaks could be around the gaskets, around the bolts, or at one of the “quick-connect” fittings that hold the hard plastic vacuum hoses to the intake.

The EGR fault may be caused by a bad Differential Pressure Feedback EGR (DPFE) sensor–which is a common failure for cars of this era, or by a plugged passage inside the intake manifold behind the throttle body. Or by a number of other things.

I think you need to find a competent mechanic with the proper level of tooling and experience to evaluate your faults and see if any of them are worth pursuing.

I have to agree with Nevada here, the very first thing I would do is get a can of MAF cleaner and spray down the bulb and honeycomb of the sensor. That is easy to do and will often solve a lot of these problems.

Then if the problem persists, start looking for a vacuum leak(s).