Does everybodys car kinda stumble slightly or kinda miss ever so lightly when they are first taking off after thier car has sit awhile? I can be at work and when I get in it to go home, I start car, idles at 1500 rpms, put it in gear to leave parking spot, depress accelerator pedal, and the car does'nt have a smooth take off. Feels like it wants to sag just a little. I can't find a vac leak but I did'nt want to install new injectors thinking it might fix the problem. Pressure regulator perhaps. I can feel a little surging on the highway when doing a constant speed. Not much though. I can listen to the exhaust and it does'nt sound quite smooth like its missing a little. Maybe its just me. Anyway to test a bad MAP or TPS? IAC is new. Might give the EGR a going once over for cleaning and I might use a shotgun barrel brush to clean the EGR pipe that comes from the manifold like a chimney. LOL.

Ken

 

when was the fuel filter changed last?

 

I have an almost identical car to you, and I also had this happen. I never noticed it on take-off (maybe because I have a manual trans) but I could feel the slight surging while on the freeway.

It happened for a couple weeks right before my coil went out. Then it was fine for a long time.

Then it did it again for about 2 months before my Ignition Control Module went out finally. It got worse with time, and a little more noticeable, until one day I drove it too long in 110 degree heat, and it finally killed it completely (the heatsink grease underneath was old and had baked away). I crawled home keeping it under 1200rpm (or it would buck like crazy) for 45 miles... Took an hour and a half, lol.

Both of those parts ran me 60 bucks new. I'd test them both.

 

When was the last time you ran codes?

 

Well. today makes a week since I installed a new fuel filter and 02 sensor. I disconnected the battery while I was tightening the hot lead going to the starter after I put on the 02 sensor. I have'nt haqd any codes since that time. In so far as the dizzy....brand new and came with an ICM. I got another coil mounted next to the accumulator, but it is'nt hooked up. Its there in case my other one decides to die on me so all I got to do is hook up the coil wire and the other two connectors and I'm on my way. Thats why I'm thinking injectors. A bad cat would'nt cause the slight surging on the highway nor the stumble because the cat aint got hot yet. Still could be plugged though. I might just gut that cat and stick a pipe through it then install the cat back on. Matbe a bad fuel pressure regulator. Would me plugging the vacuum line going to the regulator after I removed the smog pump affect the regulator?

 

As long as the vacuum line from the regulator to the TB is still hooked up it is OK.

The Multec injectors in these engines are reaching or have reached the end of their service life. I do not want to say "replace them it will fix the issue" as they are not cheap to replace. And, there still may be other issues.

Checking the resistance while hot can help confirm if they are bad. Any that are under 12 ohms are bad and need to be tossed.

There is a long thread from about 2 months ago that talks about a similar or same issue you are having. Another item was the PROM. Your car with an auto needs to have the AZTY PROM installed (part of the MEMCAL). Can check it by dropping the ECM, removing the small cover and reading the 4 letter code on the silver label.

RBob.

{edit: this thread:

https://www.thirdgen.org/forums/v6/3...-3-1l-5-a.html

}

 

If you got a brand new dizzy with ICM already installed, make sure there is adequate dialectric grease under that thing.

And if you have another coil mounted right there, try hooking the other one up and driving it for a day.

And a cat could still cause the surging or stumble, it did the same for me without getting hot. But it sure was plugged. I ran the same school of thought as you did "my cat isn't even getting hotter than normal, it can't be plugged" so I troubleshooted my heart out for another week before deciding it probably was the cat, and voila, it was.

Now I never rule anything out by logic, because all too often I've seen car trouble totally defy it, haha.

 

[Argh, there's no "C" in ignition module...]

 

TomP, have you lost control?

 

^^Ha...^^

I think everyone just has it in their head that they are hearing things...myself included.