I’m glad you’ve got your smooth idle back!
And I was glad to help
As for that code which seems to allude to a bad coil, I don’t really know the parameters of that code, so I don’t know what to say there
This may be a stretch, but perhaps the bad IAC didn’t really have anything to do with that aforementioned code
I’m pretty confident, that in a week’s time, you’ll update us that your idle is still rock steady . . . !
Unfortunately, it looks like my optimism was misplaced. It stalled on me again today. Now, it doesn’t seem to be stalling as much, but it’s also cooler today than it’s been. Any ideas what I should pursue next?
My guess is you still either have a problem with the throttle valve sticking, or a small air leak somewhere which is allowing unmetered air into the engine. Did you clean the throttle body?
Do you have a fuel pressure gauge?
The pressure should be 44.2 - 54.2 psi at idle
Does it start easily, or do you have a long cranking, before it starts?
Is it still idling smoothly?
A wild thought . . . your crankshaft position sensor could be failing and not throwing a code. Exactly that happened to one of my mom’s acquaintances. I worked on the car, and it took awhile to get a handle on it, because it happened very infrequently. In her case, it wasn’t a stalling complaint, but an intermittent no start
As for that sensor, I don’t have any specs, but here’s a thought. Measure the resistance when the engine is cold, and write it down. Plug it back in and make sure the engine starts. If it does, that is your baseline at cold. Drive the car, get everything warmed up. Get a baseline warmed up, also. Next, drive the car, and when it stalls, measure the resistance. It might have extremely high resistance, relative to the earlier readings. It might even show open circuit. I don’t have the specs, but I do know that the resistance is supposed to vary with temperature. And there is a range of what is acceptable at a specified temperature.
Another thing you can do, and this is something I’ve done . . . remove the sensor and place it in a pot of cold water, with your fluke hooked up, measuring resistance. Slowly heat the pot and watch the fluke. If the resistance suddenly shoots up, or goes open, but the water isn’t even lukewarm yet, the sensor is suspect. Because the sensor will get significantly hotter installed in the engine.
This is not junk science, but a valid test.
When it stalls, can you immediately restart, or do you have to wait?
If it won’t immediately restart, that gives you a fighting chance to do some more diagnose. When it’s not starting you could measure fuel pressure and check for spark. Better yet, hook up the fuel pressure gauge and leave it under the hood. Take a note of the reading. When it stalls, look at the gauge.
I’m just rambling, really . . .
Rambling’s fine by me. I haven’t cleaned the throttle body yet-that’ll be my next step.
The new IAC definitely improved matters, as least based on my day or so’s observation. Before replacement, it would stall and take some effort to restart. It stalled less frequently today, seems to be idling smoother (even now), and restarts right away with ease. (It was also cooler today than yesterday-still not sure on the effect air temp has). If cleaning the throttle body doesn’t help, I’ll try and borrow a fuel pressure gauge and check pressure. Next, I’ll check out the CPS. (Honestly, I’m hoping that’s not it, as that looks like a real pain to get at, but we’ll see).
Thanks George and db4690-I’ll report back.
clean the throttle body on the bench, so that you can get all the junk cleaned off properly
Isn’t the crankshaft position sensor in the bellhousing area?
Sorry it’s been a bit-it’s been hectic at work and I didn’t have time to clean the throttle body properly until now. Still no effect, so I’m guessing CPS is next. It is near the bellhousing. If I had a lift, I could just stand up and swap the thing no problem. I don’t, so I may need a couple yoga lessons to reach it while on my back! 
Well, turns out it was the PCM. Ouch. Memorial services for my wallet will be held Thursday. Thanks all, for your help!
Let us know how it turns out after you install that PCM
I’m assuming you’ll be installing a used or remanufactured PCM . . . ?
By the way, how did you diagnose the bad PCM?
Well, I was driving it last week and the check engine light went out all of a sudden. I thought the problem might have gone away-then the engine started stumbling badly. I got it off the road into a parking lot, where the engine quit and would not restart. I figured that was most likely a bad PCM, as not much else would cause the Check Engine light to go out with a problem still active.
I ended up having to have it towed. I’ll admit I punted here and took it to a trusted local mechanic-I wasn’t going to guess at a bad PCM, and I don’t have the equipment to test it. The mechanic replaced it, and I got it back today. So far, it’s running beautifully.
I prefer to fix things myself, so I wasn’t thrilled with myself for punting, but I learned some new tricks while doing the diagnostic, so I’ll take the knowledge gained and call it good.
I hope the mechanic was correct with his diagnosis
And I hope the problem is now gone for good
Well, that seems to have done it-no stalling or stumbling. I suppose 17 years is a pretty good life for a computer that sits under the hood of my car.
The same thing happened with daughter’s Honda.
The Check Engine came on, and when I checked the codes, there were three listed. One was for the EGR ciruit, one for the EVAP circuit. and one for the transmission.
I thought, what are the odds of all three of these systems having a problem at the same time?
So I turned the Check Light off and went for a test drive. The thing ran great and no Check Engine light.
A week later the daughter calls and says the Check Engine light is on again, and the engine is running rough/stalling.
So she brings it in and I check for codes again. And now there’s like seven codes listed, and some have nothing to do with the operation of the engine.
So I tell her to leave it with me, and let me do further diagnostics.
So I turned the Check Engine light off, but it comes right back on as soon as the engine is started. But the engine runs fine.
So I drive it a couple of days with the light on, and it runs fine.
Then at a stop sign, I go to take off and the Check Engine light shuts off and I can barely keep the engine running. After thirty seconds of this, the Check Engine light turns back on and the engine runs normally again.
Tester