So I'm cruising up the Chena river at about 4300 rpm and all of a sudden I started losing power and sounds like engine is knocking. Luckily I'm right next to a state camp ground with boat launch so I idle over to the bank with a trail of black smoke behind. Engine has only 94 hours and been maintained well. No alarms sounded, plenty of oil. Will start up but rpm is jumpy like its misfiring or missing cylinders running terribly. Anyone familiar with these symptoms?? I'd appreciate any insight on the matter before I bring it to a dealer.