I ran the engine through a full gallon of fuel. still having issues. I went back to the hobby store to get more fuel, but they were out of the fuel that I had bought previously so I tried a different fuel. Got home and fueled it up, and all of a sudden the engine is running like a dream. Smooth and no throttle up issues! The old fuel was 15% nitro and 16% oil whereas the new fuel is only 10% nitro and 18% oil (same brand) Is it the fuel or did the engine finally just break in? At this point, I'm just happy that its running right and will just stick with the 10% nitro fuel.