Help, I think my 1981 Merc 150 is running a little rich. guy I bought the motor from says there is no way to adjust the carbs. It idles rough for a few minutes then dies. It will crank back up & run fine for about a minute then the rough idle starts again & dies. smokes quite a bit also. gonna try changing spark plugs to see if that helps. It sat for over a year before I bought it with fogging oil in the cylinders. Once it is running & moving it does great.