1996 vmax 600 st lost power

I have a 1996 vmax 600 mountain max. I was at the lake ice fishing and fishing was slow so I went for a rip on my sled. I was at about 3/4 throttle going across the lake and all of a sudden it lost power and the rpms dropped. I stopped checked my duel exhaust both cylinders seem to be firing I shut the sled off and pulled the plugs. One was a nice brown like they are supposed to be and the other one was dark grey like primer. I changed the plugs thinking it was a plug problem. It Started first pulled I checked the dual exhaust and both seemed to be working. I headedback towards my ice shack but could not get the sled to go over 4500rpm. I tried to bypass the tors sensor at the carburetor but no change

Does anyone have an idea where I should start to find out what is wrong with it? Any help would be appreciated guys.

1996 vmax 600 st lost power