I feel like I have permenant idle issues that just never go away. my car idles between 1500-1800 when cold. while warmed up it may drop to 1300rpms and sometimes drops to 800rpms. I just had a bad o2 sensor so I replaced the burnt up Bosch with a new denso (much better quality). I replaced my tps sensor a few months ago and fixed a ton of vacuum leaks. it seems I no longer have any vacuum leaks but the car is still not idling correctly. I cleaned the maf and iac. any ideas?

 

sometimes the car will idle at 800rpms with a cold start. its just always changing. The iac has not been changed so maybe that's my problem

 

Try pulling the battery cables off for a long period. Let it get up to temp then idle in park/n for a while, then put it in D and idle for a bit. Put it back in park and turn it off for at least 20 seconds and repeat.

Over time this might help the car relearn it's idle now that there are no vacuum leaks.

 

If the PCM has never been reset I think this is a good idea...the car will idle rough for a few minutes after it learns how to idle again when the PCM is reset, but it should level out assuming that the PCM not being reset is the issue.

 

I didnt think the issue involved the PCM since it sometimes idles just fine.
I had a hunch since i reinstalled my intake manifold recently and the gaskets were on their last limb. I pulled it and found this

I replaced all 8 gaskets with new Felpro ones ($15 at auto zone with a 30% off coupon). The idle has not yet come down but ill drive it tomorrow and see how it goes. My throttle responce is SIGNIFICANTLY better, so there was definitely an issue there.

Here are the new ones on my Fast 92.

 

I also ordered a new Idle Air Control Valve since it appears to not be working correctly. Car should be perfect after that.