Thoughts on what I broke?

I was out boating with the family last night. Second trip out for the season, first trip was flawless. This time we started out strong, cruised the lake, filled up the ballast tanks and surfed for 45 minutes or so. Drained the tanks and we were taking a final lap around the lake before leaving and this is when the problem started. The tanks were empty, we had 7 people in the boat and were cruising ~20mph or so. I remember there being a few sticks in the lake and slowing down and swerving to avoid one. When I went to throttle back up the engine was sluggish and firing poorly. I didnt have any lights or sounds from the dash, but the engine was HOT. Temp was around 230 and it usually lives at 170. Engine wouldnt go over 1500-2000 rpms, somewhere around there. Sounded fine at idle, but anytime I tried to throttle up it would just bog down and sound like it was occasionally misfiring. As best I could tell backfire/misfire came from the port side of the motor. Noticeable white exhaust coming up around swim deck, but nothing in the engine bay. Back in the marina it sat for a while and cooled down some while we replaced a bunk that floated off the trailer (it was a rough night). It started up just fine this time, sounded good at idle, but again, anytime throttling up the engine would bog down/smoke/misfire. Any thoughts on what this could be? I have it narrowed down to one of about two dozen things.... Boat is a 2004 MB sports with the PCM 330 in it.