90 165hp mercruiser

i have an io and it runns great.you should check the filters first. (in the carbuatorand the water seperator) thoses filters are all was dirty in my enigine .just clean them out and it wil run good again.i can tell u a nimber of story about the io. how i made it home on 5 clyinderdoing 20 knots and not evben noticing a clyinder out till i pulled a spark plug . my father had water coming out of the dip stick and made it home from montauk (90 miles) rebuilt the engine and it ran for 8 years after. these engine are very reliable,and it does cost much for parts or even to repower.