JUST GOT A SNAPPER REAR RIDER 42 INCH CUT MOWER WITH 16HP BRIGGS VANGAURD TWIN CYL ENGINE. GUY SAID MOTOR WAS BAD. I TURNED MOTOR OVER AND IT SOUNDED GOOD. HAD BEEN SITTING IN WEATHER FOR PAST 4 YEARS. WOULD NOT FIRE SO I CLEANED FLYWHEEL AND BOTH COILS, STILL WOULD NOT FIRE SO I UNHOOKED BOTH GROUND WIRES TO BOTH COILS AND IT FIRED. SPRAYED GAS IN CARB AND IT RAN LIKE A SEWING MACHINE, QUIET, SMOOTH, NO SMOKE. GAS NOT GETTING TO CARB SO I PULLED IT AND AS EXPECTED IT WAS FULL OF RUST AND DEPOSITS. AFTER A SERIOUS CLEANING IT FIRED UP AND RAN AWESOME FOR ABOUT 4 MIN THEN STALLED. FIRED BACK UP BUT LOST MOST POWER WHEN BLADES WERE ENGAGED. CARB IS A MESS SO I WANTED TO ORDER A NEW ONE BUT HAVE FOUND OUT THAT THE 303777 FOR THIS ENGINE HAS BEEN DISCONTINUED. ALL I NEED IS A GOOD WORKING CARB TO HAVE A JAM UP SMOOTH RUNNING SNAPPER THAT WAS BELIEVED TO BE JUNK. ANY ADVISE? THIS MOTOR IS SWEET ONLY NEEDS A CARB. HELP... LOL...