Farmall Cub

Ok I think I got the spitting and sputtering taken care of. I think I found an air leak where the carb bolts to the intake.
Tractor runs better than it has since I got it. Now here is the second part of the delema.
The tractor revs up good and I let it out in 3rd gear it takes off great for about 5-10 feet then it seems like the Govenor backs the speed down.
My other cub will pull straight away from it.
What could casue this? I would like it to keep going the speed it goes when I first take off and not drop off like that. Is the govenor not set right to keep the carb opened up all the way?
any ideas would be greatful
thanks
chad

Sounds like a fuel problem to me. Do you have an inline filter? Most of them don't pass enough fuel on a gravity flow system for full throttle. Is the valve all the way on at the sediment bowl? Turn full counter clock wise. Is the screen blocked in the sediment bowl? Do you have a filter in the tank that is plugged? Is the screen on the inlet of the carb plugged? Is the float correctly adjusted? Is the needle on the fuel inlet that the float uses to let fuel in sticking. Is the float binding? Bent carb bowl. Is there excessive sediment in the carb bowl? Are the jets clogged in the carb?
Oldly enough a week coil can do the same thing at times. Very Rare.
Those are the most obvious and easiest to fix possibilities.
I guess another problem could be excessibe air leaks at the carb to intake manifold. That would probably show up on idle.
Bill

Also the cross shaft being loose where it goes into the fitting at the governoer will cause a problem with the enigne not maintaining speed under a load.