Any mechanics please help! 07 Merc 350 Mag MPI miss under load

Hi, my Four Winns with around 260 hours discovered a pretty bad miss under load between 2k-4k RPMs last fall and haven't been able to fix it this year. Here is what I've tried:

New cap/rotor New coil Plugs/wires New IAC New in gear switch New fuel filters Cleaned fuel pressure regulator

Around 36psi fuel pressure at idle, holds 40psi steady at throttle, even when missing. Scan tool showed no relevant faults/codes

Has a slight sure at idle but never dies and runs great up to 2k, then misses pretty bad until around 4k, then seems to run fine or it's just not noticable up that high.

Any help is appreciated!