I agree with Air Wizard. I have had a throttle servo with a bad pot and would work with the engine off but jump with the engine running. I also had one throttle servo that jumped and on closer inspection I found the wires frayed going into the servo. I replaced and resolderd with new wires and all was well. I've also had the throttle servo jump from a bad ignition and actually go into fail safe. That was my fault for not doing a proper range check. I will never do that again. Almost lost the plane. I would not fly the plane until this problem is solved.... by the way that was 2 years ago with a Wild Hare Edge 540.... Bill