hi all, I 'm not a mechanic. My tractor would start and run fine for a couple of minute then it would rough idle (sputter) up and down. I would recycle the engine and it still sputter but if I turn it off and wait until the engine completely cools, it would start and run fine for a couple of minutes and the problem continues. It would sputter quicker if I put the tractor under load. If I adjust choke when it sputter it would idle fine. Do I have to adjust the carburetor, if so how? Also it seems that the engine is losing its power, does not seem to have the same rev as it use to. 1956 mm 445.