Wow, I ran non ethanol fuel all last year with no issues till near the end of the season and put about 50 gallons of ethanol fuel in and my wife just reminded me that the last run of the year we thought it was sputtering then. I did treat the fuel before winterization.
Only 1 motor seems to be sputtering though, but something else to look into.

Id pull all the injectors and send them to ( Articfreinds ) Smitty on here, he'll get them tuned up and flowing correctly

Definitely something to look into, not sure how to remove them though? Would plenum have to be removed?

Yes, remove plenum to gain access to rail.
In most cases but not ll, the rail is removed from injectors from the rail on one side first before rail lifts off. To go back in install injectors in intake on one side and rail on other. It's in the manual

Finally got around to do basic tune up, plugs and wires, distributor caps and rotors, coils, IAC and new gasket sets for plenum. Started both engines ran a computer scan check no codes all seemed fine except 1 engines sounded like it was sucking a lot more air than the other
engine, Took boat out for test run and it ran very good thru idle and up on plane, stopped and opened hatch to check things out all looked good just the 1 engine with the air sucking sound, Any ideas as to what to look at?

Finally got around to do basic tune up, plugs and wires, distributor caps and rotors, coils, IAC and new gasket sets for plenum. Started both engines ran a computer scan check no codes all seemed fine except 1 engines sounded like it was sucking a lot more air than the other
engine, Took boat out for test run and it ran very good thru idle and up on plane, stopped and opened hatch to check things out all looked good just the 1 engine with the air sucking sound, Any ideas as to what to look at?