One problem related to axle shaft has been reported for the 1999 GMC Sierra. The most recently reported issues are listed below.
Ever since consumer has owned this vehicle with 48,000 miles on it at time of purchase, throttle would stick when pushing down on accelerator pedal. This defect occurred mostly during low speeds, approximately 2 to 3 times a week. Dealership was examining wheel bearings. Dealer stated that throttle body needed to be replaced.