I was in the keys last week with my 1978 Robalo center console with a Johnson 150, and after taking on 30 gallons of gas, the engine started running very rough. The engine has provided years of good service (Dad bought the boat new in 78, and it sat for about 8 years, but has been recommissioned and run well for the last 5 years) until last week. At first it would barely run, it smoked and refused to idle. I changed the inline water separator/fuel filter and it was half full of water. It had not been changed for at least 4 years. I then change the spark plugs and used a can of OMC carb cleaner in the carbs while running. It immediately ran better, but would cut out and sputter at higher RPM's. I was able to salvage the vacation and run out about 60% of the fuel in the tank, and the sputtering got less frequent. I took it to the lake yesterday and it ran fine except for one short spell of sputtering in about one hour of high RPM (4000) running. I did add some new fuel to the mix. Are my problems going to work their way out, or there other things I should check?<br /><br />Also, at the very end of the day yesterday, when I put the throttle in forward, it clunked a little bit like it didn't want to go in gear. I suspect that is a separate linking problem, but don't want to rule out lower unit problems. Any suggestions?