Hi All!

I have a 2000 SeaRay SunSport 28 footer with 7.4 Mercruiser Mag Bravo 3. Issue I'm having is motor will start bogging down and backfiring after I get on plane, and most times it struggles just to get on plane. If I let off gas it runs OK, starts fine, idles fine, runs up to 2K RPM with no issues. Here is what I've tried thus far with zero improvement:

Replaced fuel with all fresh non ethanol gas
Replaced fuel/water separator filter, dumped into clear mason jar and had zero water in it
I then filled the filter with Seafoam and started motor to see if that would "clear things out"
Replaced all spark plugs with AC gapped at .35"
Inspected cap/rotor, had white crud all inside on the contacts, thinking this was my issue, replaced both, no change
Found vacuum hose from fuel pump disconnected on underneath side of front plenum, zip tied back on, no change
Motor is running a bit too hot I feel, over 170 degrees so I have a new water pump on order, will replace when it arrives, doubt that will fix issue however
Will also be borrowing a friend's fuel pressure gauge and attach to the schrader valve and get some readings. I assume I need readings at idle and full throttle, especially at point where it starts sputtering/backfiring. Anyone know off hand what PSI I should be seeing when I connect it?

My motor has the cool fuel set up, hoping I don't have to replace that assembly since it looks like major PIA to get to.

If it's not fuel pump, perhaps injector(s)clogged? I've heard you can pop those out and take to local auto parts and have them cleaned, bench flowed tested, is this correct?

Anyone have any other ideas I need to try before I have to take it into local marina and them bend me over? Thanks!