go to home depot and get a cheap propane torch unscrew the end tip and get a 3 ft piece of hose that slips tightly over the end start up the eng get it up to opp. temp at idle turn on the propane (don't light it ) take the end of the hose and move around the carb intake and hoses if you hear the idle increase you found the leak every body that messes with cars should have one of these in there is alot of things you will use it for like doing tune up and carb. diagnoses ....ted