One problem related to camshaft position sensor has been reported for the 2004 GMC Envoy. The most recently reported issues are listed below.
Engine stalls when you slow down and the air conditioner or widow defogger is on . I have also had power surging. I had to replace the map sensor twice and the bracket and it is still showing bad. I also replace the cam shaft position sensor and the thermostat. Also the wiper on the rear will not spray any water or washer.