I'm at 1000', lid off, GYT-R full exhaust, cam mod, 165 main, 45 pilot, and 3 turns out on the screw. It seems to stumble a little (between 0-1/4 throttle) when you rap the throttle. Is that a rich problem or a lean problem? Sometimes it backfires and picks up, and some times it shuts off. If I roll the throttle on smoothly, it is awesome. Help!