1996 Mercedes c280 gas pedal problem

Your car has a drive by wire throttle. Meaning the pedal is not directly connected to the throttle body, instead it's connected to a little black box under the hood that tells the computer what you want to do, then the computer tells the throttle body to open and close, depending on the pressure you apply to the pedal. The circuitry or the motor in the throttle body has finally failed, you'll need to replace the entire throttle. body. I got a second hand one from www.Automodix.com. Go to the website type in your make and model and the part you are looking for and they will link you to a number of breaker yards that specialize in your make. Pick your part and they'll ship it to you.