Your throttle potentiometer is under your dash attatched to your accelerator linkage. If that is in fact the problem. Its a part of that horrible EML system (drive by wire throttle). The potentiometer sends a resistance value to the EML control unit which tells the electric motor on the throttlebody how far to open. If your car has this system pray that no parts fail because they're rare and expensive. You might be able to get away with cleaning the contacts inside. I've personally only cleaned my motor on my throttlebody so I'm not sure if you can take apart the potentiometer. I'm seriously considering swapping out this system for a regular cable operated system on my car. I'll lose the traction control which it was designed for but i can live with that. Sorry for the length, hope it helps!