I have a 1991 940 GLE (the 16 valve version of the b230f )
Today I was driving to school and I had a problem I've never seen to this point. I was driving and the rpms just started jumping all over, not like some car's do a little bit at idle, we're talking 400-600 difference every few seconds, while im driving! seemed to clear up if I gave it more gas though. When I stopped at a light though it started revving up, and I did'nt even have my foot on the gas! Now I've just cleaned the throttle body, and put in a new idler motor within the last year. I know the car probably needs a new timing belt (any of you know if that's something you can do easily at home?) but I can't see how that would cause this problem. Anybody had any experience with this problem?
THANKS!

 

Im pretty new to volvos and im not that sure whats wrong but maybe if you check here you can find some answers. http://www.brickboard.com/FAQ/700-900/

Later

 

Might also be a bad Throttle position sensor.

The timing belt is a pain in the A**. It is a 2 belt setup and a pain to replace.