Hi guys, newbie here. have had a problem for the last couple of seasons with the engine slowly cutting back to a very rough idle after a hard run ( 1/2 hr to an hour @ 3000 rpm). have to limp back to port and sounds like th engine will barely stay running on slow rpm, very rough. could this be a distributor problem? on shorter runs there is not a problem and boat runs well. any suggestions would be appreciated.