Rough Idle

Boat is a 2007 Sanger V230 with 5.7 Scorpion engine and 140 hours.

Three weeks ago we pulled it out of for the first time of the year (terrible spring in the NW). I put 30 gallons of new gas in, and hit the river. Didn't have any problems with the engine and everything was fine.

Fast forward to last weekend, I take the boat out and it starts a little rough. The RPM's were jumping around and it died about 30 seconds after starting it up. I drove around for 5 minutes or so to bring the engine up to temp. It drove fine and I thought all was good. As soon as I brought the engine back to neutral the RPM's started jumping around between 300 and 800 (roughly). After about 30 minutes of running the RPM's leveled out and all was good while in neutral.

Wednesday of this week my parents took the boat out and said they didn't have any problems but that the RPM's varied a bit when in neutral. I took the boat out again this AM and it died 3 times on me while in neutral. It drives perfect once the RPM's are up a bit. I tried not running any accessories and it didn't make a difference.


Any thoughts on what could be causing this and how to fix it?