With the engine stopped, move the speed control lever from Stop to Max (tortoise to rabbit) while watching the lever on top of the throttle butterly. Does the throttle move from against the idle stop to wide open? If it doesn't, the governor is in disarray. You may have connected the springs incorrectly, or it may be a disconnected or kinked speed control cable, or even more likely, a bent or disconnected wire link on the governor itself. When you remove the carburetor you have to disconnect that link, then when you reconnect it, it is easy to put it on incorrectly so the throttle is jammed open.
