F90LB bogging under load only. Newer boater!

Hey guys, brand new to the forum so thanks in advance for the help I hope to get! Anyway, my wife and I bought a sweet water pontoon 2 years ago, brand new. The first winter (we live in Florida and primarily use it for the local sandbar in the summer) I took it out a couple times to fish and we never had an issue with it. This past winter it did sit. I never used ANY ethanol gas in it, only ethanol free. It had a little less than a quarter tank as it sat and i filled it to the halfway point before taking it out the first time a few weeks ago. It starts immediately, revs VERY SMOOTH in neutral, but when put in gear and load is applied, it starts bogging down. If I open it up, it only gets to about 4500 rpms, feels pretty rough, and has intermittent “surges” where it feels like it corrected and runs great, then bogs again. It only has 64 hours and the 10 and 50 hour maintenance services were performed. Is it going to be something as simple as replacing the gas? The gas filters? Any info is greatly appreciated!

Need to do a fuel system pressure check. If fuel pressure is to specifications then I would have someone mist some gasoline into the intake when it starts to bog down. If it picks up and runs I would suspect the fuel injectors need to be cleaned.