I have a 2007 Pontiac Grard Prix turbo 3..8 engine Runs but stalls while driving

I don't see a mass air flow sensor, crank shaft position sensor, PCV Valve, Catalytic Converter causing your problems. Random stalling would occur when there is a loss of power to the processor, for example. Or, perhaps ignition spark is lost -- perhaps related to the ignition components. It's all so hard to know by guessing in theory of why a vehicle would stall. Hands on diagnostic testing is the only way to go. But focus on catching what happens when the problem actively occurs. Everything may be just fine while the vehicle is running just fine. www.repairpal.com/repair-shops