Hi, you never mentioned how the boat sat in the water without moving.The fact that you are well above the RPM range of the motor is a perfect indication that you are under propped, the boat and motor tells you at wot which direction you have to go; bigger diameter (if possible) and or higher pitch. The cavitation plate should be level or a little above the keel, The fact that you are not cavitating while underway and turning tells you the motor is not set too high on the transom. However, setting a motor too low with the cavitation plate well below the keel could cause some issues in handling at different rpms. I find it hard to believe the torque of the motor or prop could cause this. Personally 1) I would check the bottom for any warpage or damage. 2) see how the boat sits at the dock with you and your gear as you have it. 3) definitely replace the prop to turn at wot within the manufacturers recommended range. I hope this helps and good luck.Dino P.S. when this is corrected please let us know the cause.