For some back ground info go here.
https://www.thirdgen.org/techbb2/sho...hreadid=180355
and
https://www.thirdgen.org/techbb2/sho...38#post1313238

Well we finally have the timing right at about 10 degrees after finding out the timing mark on the balancer was wrong. We Jumped the a+b connector of the ALDL, waited 30seconds, then unplugged the IAC. Started the car, and set minimum air at about 700rpm, thats the lowest i could get it to go with out it dieing on us. shut the car off, and plug in the IAC. The car would now idle at 1500, and then about 700 in gear. I thought wth and thought about the problem all day at work.
The MAF has been descrened, so I thought lets try my MAF out of my 86. Well I swapped that to his car. jumped the a+b at the ALDL, waited 30 seconds, and unplugged the IAC. I started the car, and now i can get the thing to idle about 500 before dieing on me. So I set it at about 550. Shut the car off. I plugged the IAC back in, started the car and now the it would idle at about 900-1000 out of gear. I put it in gear and it would idle fine at 550 or so. This is great, I found the problem, it must have been te MAF. I shut the car off.
A few friends came over tonite to look at it. Start the Car up, and it now idles at 1500 again. WTF?? So i went through the whole setting the minimum air again, and it worked, until i shut the car off and restarted it. Then it goes and idles once again at 1500.
I tap the throttle and when the rpms start coming down it then stays at 1600 or so. Rev it again, and now it is about 1650 - 1700. Rev it again, and it goes 1700 to 1750. Is this the IAC sticking or something else I should be looking for. I am ready to start pulling my hair out trying to get this thing to idle.

 

this is probably completly off, but I had a problem where my car would idle high some times. came out(Glad I didnt tell anyone or id feel stupid) the pannel under the dash would loosen up enough it would get in the way of the gas peddel and keep it from releasing all the way.
If I messed with the tb I could get idle normal like you are doing but the first time I touched the gas peddal the rpm's would shoot up again.

Like I said your problem probably isnt this simple, but it never hurts to try simple stuff.

 

ttt

 

are you unplugging the EST wire before starting the car? need to if you want a correct idle setting. hope this helps

 

When do you have to unplug the EST? I know we unplugged it while we were setting the timing. Do we need to unplug it while we are setting the minimum air and such on the IAC?

 

Make sure the engine is at full operating temperature (at least 176°F) before attempting to set the minimum air position. The ECM will alter the target idle RPM based on the CTS input, so the engine needs to be fully warmed before making ANY adjustments.

Also, when first starting the engine, the idle RPM will start high, and slowly step down to the normal target idle RPM once an O² signal is generated and the CTS is satisfying the ECM. This can take up to 90 seconds after the temperature is normal.

There are discrepancies in manuals I've read over the need to disconnect the EST bypass connector for this procedure. Since the EST is presumed to be inactive below 400 RPM, it may not be a factor, but is right on the threshold of activity at the target minimum air RPM. In order to remove any doubt, disconnect it while setting the throttle stop position.

And as a reminder, DON'T use the dash instruments to set the minimum air position. Just as the factory oil pressure gauge is only a relative indication, the factory tachs give only a relative indication, and are woefully inaccurate for diagnostic purposes. You MUST use a handheld tach or other diagnostic instrument to set the throttle minimum air RPM.

If you need the entire procedure for setting minimum air position, I've got it.

 

yeah can i get that from you, if you want to email it to me...
Screamer27@mchsi.com or you can post it here.