Could be a varnish blockage in fuel system, evaporated gas can plug the lines blocking flow even though the pump has correct pressure. When you move the throttle past where 3,000 normally has it under a load does it start bogging from butterfly being full open for only the 3000rpms.
Replace the coil if it just boggs when you add power but the RPM still match the forward motion. If it builds RPMs and moves slow in the water could be engine coupler. If it won’t move at all in water could not be shifting into gear.