My car has an idling problem. It will idle up to about 1300 and stay there for like 3 secs and then gradualy drop to about 800 and stays there for about 3 secs and then goes back up to 1300. What could cause this? I have checked Vac leaks and replaced the IAC and ajusted the TPS and I can't figure it out. any ideas?

 

Definetly sounds like a vacuum leak of some sort.

When you checked for vacuum leaks, did you spray WD40 or anything like that all around the engine bay to find the leak?

 

Try doing a search and include the word surging in the search terms. These cars tend to have issues with a surging idle at times, especially with TPI.

 

Yes I've tried spraying brake cleaner and can't come up with anything. I just repplaced intake gaskets, runner, and plenum gaskets and TB gaskets so that should be sealed off. I have also replaced many vac lines that looked or felt brittle or just had loose connections. I haven't tried searching for surging idle so i'll give that a try. Please keep the suggestions coming. Thanks