2002 Envoy stalls occasionally

I have a 2002 Envoy that has had the check engine light coming on occasionally for last several months. It usually has been stalling after it justs is starting up (usually in the am when just leaving the house and driving down the road). I took it in to have the code checked and they said the code was related to a heater element on the 02 sensor. They couldnt really do much for it and said that I could try replacing 02 sensor but they usually dont go out this early (73K miles). Dont know what else to do. It runs fine otherwise.

Thanks

my envoy did the samething, it was a headache. You need to change the camshaft positioning sensor. if you are standing in front of the truck, its to your left in front of the head by the valve cover. the sensor is 25 dlls from dealer