I have a 1994 Mercury 200hp XRI motor on a 1994 488vs ranger

Here is the problem

The motor does not seem to have much power initially.
For instance I can not put it on the trailer it will not get the rpms it needs to push the boat on the trailer.

It has a slow slow hole shot, but eventually takes off and will run up to 6000 rpms, but it should only turn about 5800 at WOT.

It seems to pump water ok. I get about 15psi at WOT.
What could cause to not have any power?
With three people in the boat it will not get on plane.

I think it has the right prop. It is a 25p tempest