2001 Mercury 4 Stroke 90 hp rev limit issue 2000 RPM max

[LaveyT]

Greetings gear heads,
We have a 2001 Mercury 90 hp 4 stroke on a houseboat. As stated in the title the motor will only rev to 2000 rpm when in gear. In neutral it revs freely (not sure how high).
It has been like this as long as my buddy has owned it. It will get to party cove and back slowly as long as there is no strong head wind. If someone has a solution to eliminate this rev limit (or safe mode). Please provide a solution. I'm guessing maybe one wire cut would remedy this situation.
Thanks for your help!

[OnPad]

Not sure how smart a 2001 mercury 4 stroke is? Not my cup of tea, but I see your not getting much help. If it has a safe mode, it would likely be triggered by oil level, or temp. Not something a guy would want to mess with, if working properly. I would think some sort of alarm/light would be going off, but I know nothing about this engine.
My guess is fuel starvation, or prop size. Have him clean the fuel system, and try a portable tank.

[faztbullet]

shift switch?