I have a rebuilt IL6 from a performance shop, with a good reputation, but the car can rarely go through an intersection without stalling out. A few minutes cooling off and it starts right back up but dies at the next intersection. The temp gauge goes from 1/4 warm to at least 1/2 when slowing and then stopping. We’ve added an electronic fuel pump, same issue. It’s got an electronic ignition and we’ve tried using points, same issue. We’re using non ethanol fuel. No AC. Non factory I’ve added front disc brakes and power steering. Literally everything is new on the engine and it’s just can’t stay in the go mode. It seems to be vapor lock in my weak opinion but the fuel pump did not help. Thanks for any input.