Vehicle Compatibility Information For Chevrolet Trailblazer 4.2L 2002 For Chevrolet Trailblazer EXT 4.2L 2002 For GMC Envoy 4.2L 2002 For GMC Envoy XL 4.2L 2002 For Oldsmobile Bravada 4.2L 2002 Symptoms That Indicate You Need A Throttle Body Replacement Vacuum leak Poor or high idle Replace throttle body The throttle body is the part of the engine that mixes air with the fuel to allow combustion to take place. There are a number of symptoms that are often due to a failure in this part, including repeated stalling for no reason, problems with responsiveness of the acceleration pedal and stumbling or hesitation whilst accelerating. .
