There are at least 3 things that affect porpoising... Weight distribution (too much weight at the bow or too much weight at the stern) , motor height, and how the motor is trimmed under power. Setting your motor height: Your cavitation plate should be approximately an inch below the hull. This measurement will vary depending on your particular boat setup, but it is a good starting point. When you are on plane, the cavitation plate should run almost even with the lake surface. If you raise your engine too high, the prop will "blow out". Too low and the boat is sluggish under power and doesn't maneuver like it should. 1) I assume you have 5 holes for height adjustment, since that seems to be most common. If not, how many holes? 2) What hole are you using? 3) Where is the cavitation plate in relation to the hull? Higher/lower/or even with the hull? 4) If higher or lower, how many inches?
Motor height is usually the culprit. Assuming weight is distributed evenly, my first guess is the motor is set too low. However, your answers may show another issue instead or could be a combination of issues.