Check your motor and make sure the anti cavitation plate is within 1" of being even with the bottom of the boat. If you don't have tilt and trim you can experiment with how much the motor is tilted and find the best setting. There is a pin on the motor mount for doing this. If you have a tach be sure the motor will reach the proper RPMs at WOT. This will also tell you if you have the proper prop. And most important, make sure the boat is loaded evenly.
Fair Winds and Following Seas
Bill H. PTC USN Ret
Chesapeake, Va