What was found
PILOT REPORTED AT CRUISE, PREPARED FOR DESCENT, THROTTLE STUCK FUEL OPEN. AIRCRAFT LANDED AND SHUT OFF ENGINE WITH MIXTURE. UPON INSPECTION, DISCONNECTED THROTTLE, FOUND PROBLEM TO BE IN CARBURETOR. BUTTERFLY VALVE STUCK FULL, WILL NOT CLOSE. CARBURETOR REPAIR SHOP RESULTS: CARBURETOR FULL STOP EXCESSIVE WEAR ALLOWS BUTTERFLY VALVE TO TRAVEL FURTHER THAN NORMAL JAMMING PIN INSIDE BODY; THUS, LOCKING IN FULL THROTTLE POSITION.