I'm using 20/20 fuel, KB RC plug with idler bar, 10x6 APC, and Macs header and pipe. The engine starts and winds up to just over 15000 rpm, so the pipe length must be close. After 5-10 seconds (without adjusting needle), it starts to stutter and lose power, then fuel starts spitting from the carb until it eventually dies. After allowing it to cool off a few minutes, it starts easily, but the same symptoms repeat again. What am I doing wrong?

Doug