The motor runs great out of the water. When I get my boat in the water it only wants to go 5-10 MPH. I replaced a spun out prop but it is still doing this. Trim all the way up and down still no effect. The motor will kind of wind up and then bog down a bit, alsmost a sputter. <br /><br />Is the Lower Unit on this bad? <br /><br />How would I know if it is the lower unit?