Why has no one mentioned proper carburetor adjustment parameters for two stroke engines? Proper balance between idle and wide-open throttle must be considered before proper tool usage can happen.
Chain saw carb adjustments should allow the engine to idle properly when not cutting but WOT...
Are there other specifics that you may have overlooked.
Is the engine one cylinder or two cylinders? If it is a two cylinder you may have an issue where it is only running on one cylinder and when you engage the deck belt the engine is unable to power it fully and cannot move the governor...