Car starts then dies

i have a 1996 ford taurus lx 3.0 v6 engine dohc about 150000 miles…when i start the car about 5 mins the car dies…so i start it back up then it dies agin…so i start it back up then i keep my foot on gas the car stays running as soon i take my foot off gas it dies. i did have a new fuel pump in…plz help if you can

An engine can perform poorly at idle for a lot of reasons. EGR sticking, vacuum leaks, etc. Does it sound like it is idling at too low of speed when it is doing this? If so, ask your mechanic to check the idle air control valve. It may just need to be cleaned. A crudded-up throttle body can cause this symptom too.

when i start it up in the morning the car idling high for about 2 mins then it dies

i did put a new idle air control valve and i clean throttle body

i did for to tell you this sometimes when i start the car it idle high then it goes down to zoew then back up then it dies

That all does sound exactly like a wonky idle air control valve. You replaced that. Why? Is/was the check engine light on? Did you pull error codes? If so, what were/are the exact codes? Either way, the IACV needs its wiring to be be in good shape in order to function correctly. Perhaps you should check the wiring.

You should also clean the MAF sensor and check its wiring.

Warming up for 5 minutes might also be about right for the car going into closed loop operation. That means the oxygen sensors kick into the “loop” for the computer’s fuel metering. If the sensors are the originals - with now almost 20 years and 150K miles on them then it’s a good idea to just replace them anyway even if it doesn’t help. If they aren’t original or if you don’t know then checking out what they’re doing with a scantool would be a good idea.

I would also check the coolant temperature sensor.

today I put a scan tool and I got code p0300

P0300 is a quite generic misfire code (random/multiple cylinder). Misfires come from any issues with the cylinders firing correctly (air, fuel, spark, compression). All of my above comments stand. The IACV and MAF are about air. (IACV = letting air in / MAF = measuring it). The O2 sensors are about getting the proper fuel/air mix - though I’d expect to also see codes indicating lean or rich condition and/or sensor circuit issues.

Then you have spark - how old are the plugs and wires? The coil should probably be checked.

Then there’s fuel. After the fuel pump, was the fuel pressure verified with a pressure gauge? Was the fuel filter replaced when the fuel pump was replaced? You might inspect the wiring for the injectors as well.

Then there’s compression. It’s a '96 at 150K. If well maintained it could have great compression. Or not. Checking spark plugs and checking compression go very well together.

@GeorgeSanJose mentioned the EGR. If this was sticking open (“air” issue - sort of) then holding the throttle down should actually make things worse. But who knows. The EGR is vacuum actuated and it’s easy to pull its vacuum line, plug that and connector on the valve and see if it makes a difference.

@cigroller … I’m no expert mechanic at all, just a DIY’er, I hold to the basic philosophy of a diy’er, that when something is supposed to move and doesn’t, spray some wd 40 on it, and when something isn’t supposed to move, but does, put some duct tape on it. So when I want to deactivate a vacuum actuated device for testing purposes, rather than removing the rubber tube, plugging the end, then somehow plugging the port on the device, I just clamp the hose off with one of those light-weight locking-plier like gadgets surgeons use to clamp off blood vessels. Forget what they are called, hemostats maybe, but they are inexpensive and a good thing for diy’er driveway mechanics to have in my opinion. I’ve seen them available at Harbor Freight for $5 or $6, but I usually purchase mine at local flea markets where they have a better selection of sizes, longer, shorter, etc, and they have ones there that have bent jaws too. I’m not sure whether pro-mechanics use these, but they’ve saved me some time and grief over the years.

@GeorgeSanJose, I have actually disabled my own (Ford) EGR this way so that I could drive around - also something of a DIY’er trick. I think I still have a golf tee (right size for the vac line) and vacuum cap in my glove box. It takes about 10 seconds. I’d do that before the clamp if I’m going for a drive - but obviously it doesn’t sound like this guy is driving around anywhere, so either way.

Of course, either method only works if the issue is vacuum related. If the valve is just plain stuck open it won’t matter either way. (Mine was vacuum related. I needed a new vacuum solenoid.) For that you’d have to pull the valve and install a temp blocking plate.

Yeah, you can’t unstick a stuck EGR valve with the vacuum line. I was thinking maybe pro mechanics wouldn’t clamp the rubber lines as a routine diagnostic procedure b/c it might damage them and cause problems for the car owner later.

Nah. I’m not a pro mechanic either, but its just a vaccum line. Dirt cheap. You can also give it a quickie pinch with your fingers on the ford set up - skinny soft rubber line.

FYI: There are special pliers you can buy for clamping off lines without really damaging them. I don’t have a pair, but I think I’ve seen tester post a pic or link or something. When I win the lottery I’m going on a tool buying spree and then I’d like to have some.

i did put new idle air control valve and i did throttle body