Are you sure it needs repaired, or just re-calibrated?
To re-calibrate: Disconnect Battery for a minute or two. Reconnect battery. Depress gas pedal to floor, hold it there for one to two minutes. Turn on ignition with pedal still depressed, DO NOT START, hold it there for a minute or two. Turn off ignition. Remove foot from gas pedal. Start and see if it runs better. If not you may repeat the process but have someone disconnect and reconnect the battery while someone else holds the pedal to the floor.
I got this from my brother who was trained in California, for emission control inspection/repair. It's worked on our GM vehicles when changing altitude ascending and descending mountains.