Hi, and welcome to the SeaDoo forum.
I have a 96GSX (same hull similar motor) and it's very stable, so I really don't know what to tell you. Is the ski only tippy under power? If so maybe check the motor mounts. I also might be what you are use to riding, if you been riding 4-tec skis which are bigger and heaver I could see where the ski might seem tippy.
Lou