on your go tech engine have you tried a different pipe at all and are the seals any good , i have had trouble with pipe and tuning and it was something with the baffles in side the pipe not suppling sufficiant / erratic pressure to the tank also i have been told that approx 12 inches of pressure tube is the ideal length running to your tank as the pulsation from the pipe can make a big difference to fueling and tuning after the tank has been filled... i have had similar problems with different engines but after doing those few things and checking everything over problem went away in long finals give it a go nothing to loose