Re: johnson 60 running rough at idle
did you remove all the jets? what is your idle speed, you have to set idle higher on muffs, so it will start in the water, then fine tune idle speed in the water, with the motor in gear.
also Ethanol and fuel lines
replace all fuel line with Alcohol resistant lines. Ethanol deteriorates, the rubber lines, then they start to sluff off on the inside, going directly to the carbs. Settling to the bottom of the bowl. Contaminating the carbs high speed jets. clean a rebuild carbs, flushing fuel line before connecting to carbs.