I have a fast track with the 20 hp Honda motor. It has started to run rough and shutting off. List of things i have done Changed spark plugs Cleaned Carb Added fuel cleaner Changed Air Filter Changed Fuel Filter It will run but on sharp turns spits and sputter and cuts off It seems like it is not burning all the fuel it spit sputters and back fires If it does Idle I can shake the mower and it starts it all over again. HELP!!!!