Pontiac Repair: idle surge, vacuum leak, grand prix gt

Question
My 99 grand prix gt 3.8 service engine soon light is on. When idling the engine surges. The tach drops to around 700 rpm then surges up to around 1500 rpm. Runs fine down the road. Cruise control holds.

Answer
Hi Larry:

well If I were to guess I would say it's an issue with either a vacuum leak somewhere or the MAF sensor is acting up. If the lamp is on then stop by one of the big bx auto parts stores and have them scan the car for codes and see what the code(s) are in the engine computer and go from there. If indeed it has a MAF code just unplug the sensor and try driving it and see if the surge is gone It will hesitate from a stop but the surging should be gone if so the sensor is more then lilley bad. good luck :)