I'd let the engine run for a few minutes to warm up, then with someone helping tilt the plane straight up at full throttle and try adjusting the high speed needle. Then check to see how the engine transitions from idle to full. If it works good that way, then hold up again at full throttle then cut the throttle and see how it reacts. Also watch your fuel line when you raise it up, for air bubbles due to leaks or vibration.