I recently started having issues with my 23HP gator taill getting on step. I found out that some bad gas was ran into the motor so I took the carb completely apart and cleaned it 3 times. I just changed all the motor seals, put new rings, polished the bores, re-seated the valves and set the valves.

Motor is turning 4000 RPMs without a load on the trailer. When I put it in the water it is turning approximately 3700 - 3800 RPMs but it will not get on step like it used to with just me in the boat. Could it be that the clutch went out or is going out? Anyone had this issue before?

Do a leak down test on the cylinders, with the work you did, you may not be sealed somewhere.