I have gone through the fuel system and found no leaks.  I replaced the 'O' rings in the carb and remote needle.  I have isolated the fuel tank from the airplane with foam. called the manufacturer about needle settings. Put a deflector on the muffler to increase back presure.  Adjusted the needles till I had to replace the 'O' rings again.  Put a glow in with a idle bar and still have problems with it going from low to high rpm.  I t will just die. If you run it at low or mid throttle for awhile and go to full throttle it wil die. I had a plug with a 'H' on it and tried it no help.  The engine is on a Uproar which puts the tank pretty low when compared to the carb so I am thinking a different engine....?  The engine will run good and transition good then start in with the problems after about a minute or two.  I may try the steel wool to get more pressure.
Any other ideas