I have a magnum engine that seems to be vibrating and afraid of damaging something while in flight is it normal to have the engine vibrate excesively? and then it dies out at idle what could it be? i checked the valves with a feeler guage and its set to .004" any thoughts to this? one thing to note im using 10% fuel for breakin and my prop seems to be balanced pretty good its a master airscrew 14-6