does the tank have a anti drainback valve,also known as a check valve?

if the pick up tube was cracked(at the threads towards the top of the tube) the engine would run fine with a full tank of fuel,then the engine would start acting up once the fuel level starts going down...

Does this sound familiar? if you do find a cracked pick up tube order 2 of them but the tube part made out of nylon..they wont crack..

proubably not your problem but worth a shot.have a mpi fuel injected motor and the sea water pump on the motor was weak,causing fuel to evaporate.let motor cool down would refire every time.not fimilar with your set up but the sea water pump is quick and easy to check.my engine didnt over heat or anything.just wouldnt restart hot