99 mercury force 75hp problems running under load help please

I have a 99 bass tracker pro 175 moth a mercury force 75 I am having problems with. This is my first boat and I'm completely new to working on boat motors. What's going on is when the boat is in the water and under a load it takes off mine on the hole shot then Bogs down and runs at about 2500 rpms full throttle and normally runs at 5300. In neutral it's starts up and runs fine and with boat muffs on it in the yard it runs great in nuetral and in gear. I have checked my compression I have 110 psi at all three cylinders. I'm stump could it be coil packs? Could it be fuel? Any help would be greatly appreciated thank you in advance

Open the idle mixture screws out (CCW) one half turn.

Jeff