150 Pro XS running irregular at mid throttle

Running a 150 Pro XS in saltwater for about a 2 years (250 hrs) and it has started to cut in and out in the mid throttle range. Already had fuel pump replaced after original died with very few hours on the motor. Worked fine with new fuel pump for a long time. Now it runs fine at idle and wide open but surges and slows down dramatically at the mid range throttle positions. Already changed fuel filter, always run fresh ethanol free gas.

Is this a fuel injection problem? Bad Coil or plug?

The boat is an 18' flats boat.

Motor #s

1150P73FY

2B021062

150L PXS

Any clues on how to fix this? Common Problem?

Thanks for the help!

What is the MAINTENANCE history on this engine?

Are you running ONLY the water separating filter inside the engine cowling (or has another possibly been installed in the boat)?

SOUNDS like a fuel delivery problem, though it's entirely possible that a "glitchy" TPS is the cause.

TPS can be checked on the Computer Diagnostic System, by performing a voltage "sweep" test (preferably in GRAPHING mode), while watching for glitches in the mid-range of TPS movement.