I can drive normally for about 1/2 hour, go full throttle no problem, but after that the machine just bogs down, I can't go more than maybe 1/4-1/3 throttle. Seems to be when the engine gets heated up, not hot like overheating but hot from driving when this happens, after I shut it down for 10 mins or so, it will run fine again for a while. Any help is greatly appreciated.