I have an older 7.5hp Ted Williams motor air cooled that will run perfectly for a while at full speed until it starts getting hot. After a while at full speed, the motor will kind of bog down and then shut off instantly. It will start right up after this happens and run just fine for a little bit and then it will do the same thing again. It also kind of sputters when it is given full throttle. Other than that it will run perfect all day on lower rpms. Idles about as good as new. It also starts on the 1st or 2nd pull without fail. The carb was cleaned and everything seems to be alright. Any thoughts on this would be greatly appreciated. Thanks