1998 Mercury 75 hp elpto

[rutpup]

When I'm driving the boat with just me in it, it gets on plane just fine. But when I add people or cargo it will not get out of the hole. The motor is on an aluminum 1998 Ranger Cherokee boat. All three cylinders test at 120 psi. I have always used non-ethanol fuel with stabil. When running the engine with the muffs if I unplug the coil pack/power pack the engine runs noticeably worse. Also 4500 rpm's is all it will muster.
Any help is greatly appreciated.

 

[rutpup]

Just experimented with changing the coil packs to the different 3 cylinders, #1 and #3 still no change, when I unplug #2 it dies with any of the three coil packs plugged into it. So it appears that all the coil packs are good. I'm completely lost on what to check next...