Have an Ariens snow blower and engine will stall at full trottle but if you move the trottle to 3/4 will seem to run OK but very slow. Any ideas, the snow blower is three years old.

Hi,
Sounds like a fuel delivery problem. At full throttle the main jet is in full "force" in that it is responsible entirely for fuel delivery. At part throttle other circuits are used also and it sounds like it is running but "starving" for fuel. My recommendation is clean the main jet, in the bottom of the carb. There is a likely some form of "trash" buildup there. Do not neglect to look for a very small hole at a slant and just above the lower threads. That could be your culprit if there.
Peace,
Clarke