once top speed is reached the nose dives and
the boat looses plane and starts plowing the water. I have the motor
angled
as far as possible on the mount bracket to lift the front end up but it
still does not get the boat on plane at top speed.

When the trim is set out to the max, is the foot of the motor angled out
past the perpendicular to the line of travel? Does the thrust from the prop
rise to the surface at speed? Maybe you have a highly angled transom, and
the motor needs mount-wedges(shims) to get the desired trim angle.