I agree with Longhunter. While I am not familiar with M37's specifically, what you describe is typical of a vehicle with vapor lock. Another thing that could be wrong is a malfunctioning ignition coil or condensor. They run fine until you shut it off, then they heat sink and won't run again until they cool off. Do the usual checks for spark and so forth to make sure it's not something as simple as a switch. A tune up is always a good idea too, so that may clear up a points/condensor problem. Check the battery also as sometimes they can overheat from overcharging and will not put out a decent amount of current to start the engine. The only other thing that comes to mind is a bad starter. Sometimes when they get hot, it saps all the juice to crank the engine and doesn't let the ignition system fire. Just my .10