My 2003 subaru outback wagon, manual transmission, starting revving about 1500-2000 rpms higher than normal today. When I put the car in neutral, the car revs high sometimes increasing in rpms. Also when i left off the gas the car doesnt decrease in speed or rpms almost like the gas pedal is sticking. I revved the engine while in neutral a few times to try to see if I could get the rpms to drop but that didnt work. I had two belts changed yesterday (excluding the timing belt) and everything was fine with car until today, after driving 70 miles. Please help!
There are three possibilities: stuck/dirty throttle plate, stuck/dirty IAC (idle air controller), or vacuum leak. If your handy and even just slightly mechanically inclined, cleaning the throttle body and IAC is an easy task with a $10 can of Sensor-Safe Throttle Body Cleaner. Spray the linkage and make sure the throttle will open and close all the way smoothly. Also make sure there is no sludge build-up on the bore, plates, or in the passages.
The vacuum leak is a bit harder to find. First, check the condition of all your vacuum hoses under the hood. Replace any that are questionable, one at a time to keep from mixing them up. There should be a vacuum line routing guide under the hood if any are broken or separated.
BustedKnuckles is exactly right. I would just add a little to the sticking throttle plate. In addition to inspecting the internals of the throttle body, inspect the entire throttle mechanism & linkage all the way from the pedal to the throttle body.
I don’t know the belt set up on these cars and the belt replacements very well may have nothing to do with it. However, it is certainly possible that something like a vacuum line was dislodged or otherwise buggered while the belts were being done. Sometimes you just pop the hood and something stares you in the face. So open it, find the belt, and scrutinize the entire area & surroundings.