I'm a newbie here so I'll try to get this right the first time. I have a 96 bonny se w/121k.I'm the 3rd owner of this car and have had a nagging fast idle issue since ownership.At first the car would idle down on its own to 1000 rpms, never lower.In winter it would start out at approx 1500 rpms and get higher .It will go as high as you will let it, 3500rpms and up. Yesterday temp was 3degress, and at start up idle was 2500rpms. I've replaced temp sensor,IAC valve and PCM, and PCV valve. NO codes, other than Cat.Conv. previous owner removed it for the heck of it. In the beginning when the car warmed up it would idle down on its own. Now sometimes at a redlight it'll speed up on its own while in gear. Any suggestions? ........Thanks in advance

Have you cleaned the mass air flow sensor (MAF), and the throttle body? (TB). If not, may want to start there. Procedures are in techinfo (link at the top of the page). Also check for any vacuum leaks. Welcome!

Besides the MAF, the TPS or throttle position sensor might be sending the wrong values. This sensor can be checked with a stanard mutlimeter if you don't have a scan tool available.

Holler back and we can toss in the procedure you'll need depending on the tools available.

The most likely suspect is a missing O-ring in the PCV valve below the MAP sensor in the UIM.

At idle, remove your oil fill cap. Notice anything unusual? Describe what you observe.

A little more history and then answers to ??'* First off I've had to replace the intake twice in the last 60 k. The first time was due to gm defect from the crappy intake. The second time was due to being in a rush and forgetting to take the metal piece for egr or what ever its called off the old intake, and putting it in the new one, metldown lol my bad. Since then a new tps was put on but no difference, throttle body was cleaned when replacing intake the second time.Tps was returned to parts store since it didn't cure the prob. Pulled oil cap off at idle today and no difference it came off easily, and no noticable noise, whistle etc. I do know the car was wrecked at one time, and repaired and prev. owner had driven it very little over the last 3 yrs b4 I got it. I've had it to the dealer and I changed all the parts they were going to replace at twice the cost.When the car idles it fluctuates approx 500 rpms like the cpu is searching for the idle speed at cold start. As for vacum leaks I sprayed all the vacumn lines w/ no luck finding any leaks.

so since there is no noise sucking sound etc. thats the prob? I'll replace the pcv valve and o-rings and reply back when it gets a little warmer to get at it. Thanks a million guys your a great help.

I have the check engine light which stays on due to no cat. conv., other than thats it. Should I be checking one or two o-rings? I looked at the gm shop manual, and in the diagram it only looks like there is one o-ring. Is there one in the manifold, and one that is attached to the pcv valve?