- Jan 25, 2013
- 62
I have a 2003 GMC envoy XL 4.2L with 181,000 miles. have a slight rough idle and vibration when idling. it is worse when a/c is on. already cleaned the throttle body. what else could it be? we bought it with 100,000 miles in April of 2012 and only thing i have done to the engine is new plugs when I first got it and new ac compressor last month. normal maintenance fluid changes are all up do date