2002 Chevrolet Avalanche 2500 Remote Enter Vehicle Start Aproximatly 15

I have a 2002 Chevrolet Avalanche 2500, I use my remote to enter the vehicle then start it. Aproximatly 15 minutes after driving the engine shuts off. I have to make it look like I exit then wait 10 minutes to use the remote to enter , then the engine will start again. It is not akll the time, mainly sparatic.