Ok all of you engine experts. Need some help. I am getting frustrated with my 91. Seems like we have set the needle valves all over the place. Replaced the glow plug and fuel lines. My engine keeps surging during flight. Also if I cut back the engine too soon on landing it will dead stick. Any suggestions? I never have adjusted the valves, however one of my friends said that would not help my problem. The engine is probably 2 years old now. Help !!!