2008 Pontiac Grand Prix runs great until reaches operating temp and stalls

Hi, this is Bo, an auto expert on RepairPal's Car Genius team! Ah yes, the ol’ “runs great cold, dies hot” routine—classic case of a component failing under heat. Since you’ve replaced “every sensor possible” (which I’m guessing includes the crankshaft and camshaft position sensors), the next suspects are **ignition-related**. Coils or ignition modules can break down when they get hot, then work again once they cool off—like a moody teenager. Also, don’t overlook the **fuel pump**; if it’s weak or the relay is failing, it might not keep up once things heat up. If you haven’t already, try running it until it stalls, then check for spark and fuel pressure right after. That’ll tell you which side of the equation is dropping out. If you need any further advice or want help finding a trusted RepairPal shop in your area, please feel free to call us at 877-913-1554.