Do a google search for “Z7 hooked hull.” It sounds like you might have one. If you have a long straight edge like a level place it length wise (bow to stern) at several places on the hull. Some are so bad there are gaps between the bunks and the hull. There should not be any when it is on...
The FIRST thing to do is check for a hooked hull. Do not add a foil yet. Z-7s are known for this. It means the boat was pulled out of the mold too early and it sagged. If you are the original owner, and it is hooked, Tracker will take care of you.