unsuccessful boat trip yesterday on the lake... 3 year old Yamaha engine was sputtering off/on (Never died) at both idle and trying to get on plane. Decided to turn around and put her on the trailer (last day of season) to investigate on land. I checked the fuel/water separator, oil, fuel lines, etc and don’t see anything out of the ordinary. I have always used ethanol free gas and did the full annual service about two months ago (oil, filters, gear oil, etc)... engine only has 75 total hours on it. I swapped out the fuel/water separator filter and checked for water.. nothing. Bad gas? Plugs? Something worse? my Motor is under the extended Y.E.S. Warranty and has just shy of 2 years left... any recommendations?