VIN 1GMDX03E4WD206861 3.4 L eng 4 spd auto trans Symptoms are heavy shudder/surge at 30-35, 50, 65-70 mph Engine can be heard surging, no codes (eng or trans), must be at a constant throttle (tps at 15-22 %)under very slight load, will occur moments after tcc ... Login to read more.