Evolution .46NX in my Superstar...I am running the recommended tower super plug, that is actually made for the 4 stroke engines. 15% Nitro...from Hobbytown USA. I have noticed that the engine feels sluggish and has a slow response. If I run it very long at low throttle, then increase throttle, it spits and sputters....cant figure it out. The only time it really bugs me is if I come in to land a little hot and overshoot the strip I had set up to land on. I then pull up, advance from idle to about half throttle, and it spits and sputters for a second while trying to climb out. This engine starts very well, climbs with almost unlimited vertical, and will cruise my Hobbico Superstar beautifully at about a quarter throttle. I set the mixture like it stated in the manual, a slight turn back from the point where it made the highest RPM....

Anyone have any ideas???

I appreciate any help I can get...