Do NOT use the idle mixture needle to lower the idle. I would start all over with the needle settings. Whatever the base needle settings are in the manual, go 1/2 turn richer than that. Set the idle gap for .5-.6mm and tune the engine from there. Always set your main needle first for a nice clean and smooth run up to WOT. It should sound clean. Next set the idle needle so it will transition from idle to high throttle smoothly but still drop immediately to idle after letting go of the trigger. After it drops to idle, listen to the engine idling. After 3-5 seconds the idle should drop slightly and stay there. It should slightly load up if left idling for 15-20 seconds. At 30 seconds it will probably flame out if you burp the throttle too quickly. All of your performance tuning should be after the engine is thoroughly warmed up - usually 1-2 tanks operating above 200F is usually adequate.