Hi Scotty, pretty busy page you have here... I have a couple of questions. My 2006 grand prix pontiac's temperature gauge is fluctuating to high and back to normal but not overheating. My question is can this situation cause the car to sputter and stall? Or, can the high temperature of the engine affect the operation of the crankshaft sensor and that's why it stalls. Or, can it be my crankshaft is going bad? Thanks for your response in advance.

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Sounds like a bad thermostat or cooling fan - the crankshaft and crank sensor are not the problem, get the codes from the computer then see Scotty's video on head gasket leak and overheating