Re: higher speed "stall"
 

Like was said before - either fuel, air, or exhaust plugged up. Don't look for something exotic and complicated right now like electrical problems.
After you soak the carb in cleaner and you completely empty out the old gas and refill with fresh, and check the air filter, take a look into your exhaust. Feel around with a coathanger or something. Sometimes a creature, animal or bug, can set up shop in there with a nest restricting the exhaust flow out of the engine.

Re: higher speed "stall"
 

Is that sort of like having a bug up your butt ?? :shocked:

No, sorry, that's something entirely different !! :whistle: :crackup