A lot better, but still revving

I have to drive up a steep incline and back into my parking space. After I put it in reverse and start backing down the hill, the motor will start revving. It will still rev when I restart later. After I get on the street, and turn the motor off for 5 seconds and restart, the revving has stopped. This is the only time it happens now. Any suggestions?



History: I had a revving problem that would happen 2-5 times a day. I could be driving and then the motor would start revving and accelerate. It may or may not stop it unless I parked in the sun. It started only in very cold and icy weather and then even in warmer weather. The dealer has replaced the throttle position sensor (engine warning code). Hellokit suggested cleaning the iac valve (idle air control) and the throttle linkage/plate when they replaced the sensor. Supposedly they have done this. They also had to readjust the computer for the sensor.

Olds Aurora 3.5 2001, 65,000 miles