+1 on preheating the motor i have done it for all but 1 tank im at roughly a gallon on mine and the 1 time i did not preheat the motor it was acting as you describe it took about half a tank to warm up and was at perfect tune it was way rich while it was warming up so i would preheat to about 180 run a few laps and tune from there and as stated above get the low needle set first and tune the high end from there. its hard to tune the motor before its up to temp