What causes a riding lawnmower to cut off when the throttle lever is pushed to fast?
One thing that could cause that is restricted fuel flow TO the carb.
A partially clogged filter might allow enough fuel to pass to allow the engine to run at low speed, but be insufficient for high speed or under load.
More details, such as the Sears 917.xxxxxx number or engine brand, Model & Type/Spec would be useful, assuming you want help.
What causes people to post the same question twice?