I have a 1997 1100 STX and today mine started doing the exact same thing. The only difference is that mine did not fill with water. I took it out over the weekend and it ran great. Today started out fine but after 10 min the motor started to die and then I couldn't do anything but idle. I changed the file filter and the plugs, put the ski back in the water and it still had no power. I brought it back home and flushed the motor. While flushing the motor would rev up like it should but the motor and the water coming out of the back was real hot. I am also at a loss and any help would be great.