is the motor fine internally? clutch good? whats the glowplug look like? an engine stalling on throttle "usually" only happens in a lean condition, a rich engine will gurgle and blubber when you get on throttle and may stall but will be on the initial pull after loading up with fuel off throttle, if you pull 20-50 feet out of the corner and then stall its probably lean.
an engine that is wore out internally, typically a streached rod can cause similar issues but your glowplug coils will start to look pushed in and the engine will have a noticable bit of play when it gets into compression.
if thats not the issue pull the carb apart and make sure its good and clean internally. set the high speed 2.75 turns from closed, start with the low speed 5 turns out from closed(pull the carb slide open while you do this) and slowly work your way leaner from there.