97 PA idle problem

Our 97 PA will not idle correctly from time to time. Sometimes it will settle at around 1500 rpm's and as high as around 2500 ... this is a bit unsettleing when you are slowing for a stop sign or similiar. If the engine is shut off and restarted right away it idles down correctly. I have popped the hood when this happens and tried snapping the throttle quickly but it is already at the idle stop but the engine is roaring. Again, this is hit and miss as to when it will happen, it is frequent though.

Any thoughts?

Thanks

Sounds like your idle air control (IAC) is malfunctioning. Try removing it and cleaning the seat & pintle with carb cleaner. If you have access to a scanner, check IAC counts. In addition, check the TPS function with a scanner. You should see a progressive voltage increase from idle (0.5v), up to WOT, where it should read around 4.0v to 4.5v. The engine does not have to be running for the TPS testing. Check several times for repeatability.