I recently purchased a 98 big bear 350 4x4. All it needed was a battery and a good carb cleaning and she was puring like new...until I took it is water. Now this wasn't a lot of water maybe 8 inches deep, but when I hit the hole I lost a lot of power like it was trying to die. It pulled its self out and as soon as I hit dry ground it was right back to running normal. I got home and checked all my vents, carb, air intake etc. Gave all electronics a good coating of dielectric grease and sprayed then with silicone spray on the out side. Went a couple days later and same thing. When I got home this time I sprayed it down with a garden hose to pinpoint the problem. I sprayed it all over and it never tried to die until I sprayed the outside of the exhaust (muffler) then it started to big down and eventually died. What is causing this and how do I fix it?