I have a 2006 Kodiak 450, and just recently encountered the same problem. I was going through some swampy areas and would choke, sputter and stall. I could start up again, but as mentioned by someone else, had to keep on throttle to keep from quitting again.
I've never had any problem with even the deepest water (ie up to headlights @ times), until just last week. I had just installed my new tires, and obviously wanted to get in to the slop! Guess I'll get out the di electric grease and cover up my connections, ...wonder if I knocked a wire loose during the install??

 

I've never had that problem, but I dont hit it real fast. Like was said eailer try easing in one time and see if that makes a difference. I had mine up to the seat in water and it just keeps on going. It that squeakie back brake that I'm going to work on real soon. Anybody recommend a good replacement pads?

 

i have an 06 grizz that did the same thing when it entered the water. I cut a couple of long strips of plastic about 2 inches tall on the plastic panels that cover the engine. Then i wired on some mesh with 1/2 inch squares to keep the big stuff from getting into my engine. I havent had the problem since. ( just watch your legs it throws quite a bit of heat ). It gets rig of the steam really fast.

 

Update,

Well I pulled my plug, cleaned it and put a coat of dielectric grease on it and the terminal. and went for a ride yesterday... no problems at all, unfortunately we didn't get especially wet, but there were a few good swampy spots I went through, water up to the winch anyway. So that seems to have done the trick!

 

You can drill a few holes in your rotor to get rid of the squeak... Did that on ours... worked like a champ...

 

i know the post is old but after the dielectric grease did you ever have the problem again