car: pontiac bonneville, 1996, v6, 105K miles.

While waiting at a stop, I noticed that the RPM slowly started to increase all by itself! 700 to 1000 to 1200 to 1500 to 1700...

At this point I put the car in park and RPM jumped to 2500+. Turned off engine and turned it back on, everything back to normal.

I've also noticed that while slowly going through a parking lot, the car won't idle down but will stay at a "high" RPM (say 2000) - forcing me to stay on the brakes to keep from going too fast. After a bit, things settle down and everything is fine.

No error codes.

Any ideas?

Check your TPS (Throttle Position Sensor).

Your throttle body or accelerator linkage may be ceasing up because it/they are dirty.

TPS(throttle position sensor) uhmm this could be bad and in my experiance the same thing would happen at idol. I would definatly get it checked and if bad replaced.

Had the same problem, car would idle high for no reason, I changed the fuel filter and problem went away That may help...

I'm weird but... when I start to have fuel problems regardless of whether I know what it is or not I put some Marvels Mystery oil down in the gas and it keeps the fuel system nice and clean (from what I can tell).

took to dealer today, they say its the EGR.

:P I cant understand why everyone here takes there cars to the dealership, man I wish i had that kinda money. They always want to charge like twice as much as a regular mechanic. Oh and if you go searching for a mechanic always ask them if they charge by the hour or by the book price (dirty rotten suckers).