Hi!!
Did you found the problem??

At high speed, My drive also won't trim....up or down...

but at +- 3600 rpm, all is correct, at 4600, can't trim!!

Sorry I havent been on in awhile. Most everyone was right, the hydraulic lines were crossed, but Tubbstoy2 hit the nail on the head, they were backwards at the manifold. I flipped the lines around at the pump and it now works perfect. I flipped my trim switch upside down so I can use it until I fix the problem correctly. The manifold is way under the motor and Im going to have to lift it to get at it. All that can wait for the winter though. Thanks everyone for the help.

Phil