Need Help, CEL and Crappy Idle Problems.
 

Ok, I've spent the last 2 hours looking through old posts and couldn't find anyone with the same problem or someone that suggested something I haven't already tried so I'll make my own post to add to the ever growing library of FC problems.

This is for a 90 NA.

When dead cold, doesn't matter what temperature outside, I start the car and it will fire, sputter for a second or so, at this point I get a half second flash of the CEL, and the idel will crawl up to about 1500rpm and sit there for about 30 seconds, at which point it then begins to bounce between 1500rpm and 1000rpm for about 5 minutes, then it will settle off and begin idling somewhat normally until it hits about 800rpm, then it bounces between 850rpm and 500rpm.

However, if I say turn the car off to go in a store and come back maybe an hour later so that the car has cooled off, the AWS works as it should, there is no bouncing, it just settles at 1200rpm until warm, then it sits at 800 and will start the bouning between 850 and 500 again.

I have done everything I could find that was suggested for an irratic idle, things such as clean BAC, adjust TPS, change TPS, etc. I'm running out of ideas and about the only thing I have left to replace is the Pulastion Damper.

I mean, I'm sure something is wrong due to the CEL flash, but the damn thing doesn't seem to stay on long enough to record a code.

Well, thats it, I'm at a loss, I hope someone here can help out a bit.

Thanks for reading yet another idle related novel.

If the CEL pops up it should be stored until you clear it. Just making sure but have you actually tried to pull the codes?

Yea, about 13 times, All I get is nothing. Now that I've thought about it more, I also get the CEL very briefly at exactly the same place on the same road every couple nights, its a slight uphill, I'm typically at about 3k in 3rd and just at the peak of the hill it will flash. Not sure if its related but yet another example of the light flashing with no code records. I know checking the codes works cause I used it to determine the O2 sensor was toast. But since then the car has come up clean.