Good one Ed .
I still say mount the engine in a test stand as I said earlier (and several others have agreed) to make sure its really the engine thats giving you the problems and not a fuel delivery situation.
Also I would then check all the bolts for tightness and loosen the carb and re tighten while pressing down to make sure the Oring is sealing properly.
The reason for asking what sort of plane and mounting was that a inverted engine can give a person troubles at times ,but this shouldn't be your case ,if anything you will find the tank is low in that trainer not to high
Good luck with it .