2002 Envoy Shuts off when A/C is turned on

Everything works fine until I turn on A/C or Defrosters..then the Truck Stalls and eventually stops...I have changed Spark Plugs and Coil Caps (Equivilant of Spart plug wires, I think)....But Still same problem

could try this,clean the throttle body bore.here is a bulletin showing you how.Engine Stalls When Air Conditioning Is Turned On at Idle2004-2007 Buick Rainier2002-2007 Chevrolet Trailblazer and Trailblazer EXT
2002-2007 GMC Envoy, Envoy XL and Envoy XUV
2002-2004 Oldsmobile Bravada
2005-2007 Saab 97xEngine may stall with the air-conditioner on and or while adding additional loads to the engine at idle. An example of an addition load would be turning the steering wheel left or right with the air-conditioning on. This type of stall usually occurs during idle or slow parking lot maneuvers. This concern may not set any diagnostic trouble codes.
Clean the throttle body bore and the throttle valve plate using a clean shop towel with GM top engine cleaner, GM P/N 1052626 (Canadian P/N 993026) or AC-Delco Carburetor Tune-Up Conditioner, P/N X66-P, or an equivalent product. this should help.

Thanks!!!!!! that worked like a charm....