I have a 318ti we put in a 99 S52 M3 motor. Everying was great until it started to get warmer ouside. Now it starts and runs great when the motor is cold. After it warms up you get a ramdom misfire on 1-6. When it first started you could turn off the key for 5 second and it would stop. Now when the motor is warm it will not even turn over if you try and restart the motor. You can hear the fuel pump running. You can also hear the starter click( but it don't crank) maybe once. I ran the car up to temp yesterday in the drive way. Turned it off and it would not turn over. Let the car cool off and it will start up. Now I let it run at idle with the hood closed for about 15 minutes, and the car died and would not restart.

I tried swapping out the ECU, changed out the system relay, checked the connection. I even tried my local BMW Dealer. They didn't want to work on the car since it was not OEM. They suggested adding another fan to the engine bay, and changing out the fuel pump. The engine it self doesn't over heat, and I can't see it fuel starving at idle. I has at the track a few weeks ago, and it never fuel starved.

What would cause the misfire and the engine not to start and even die when hot?

Thanks
Don