SHUTTING DOWN AT 3500 TO 4500 RPM RUNS GREAT UP TO ABOUT 3500 THEN IT JUST STALLS LIKE ITS OUT OF GAS SAT FOR 8 YEARS ON DAVITS HAVE DISMANTLED AND CLEANED CARBS FUEL TANK & LINES DID COMP CK. BAFFLED OH JUST STARTED SHUTTING DOWN WHEN I PUT IT IN REVERSE HELP!!!!!! 