I mostly use my quad for work, carrying myself and equipment to places on the land, and it's steep hilly land so a lot of it turns into a bit of an adventure, but when my sons were young we made a mud hole with a skid pan next to it and we had so much fun and so many laughs over there. Mud is good !
Its possible that your choke plunger could be stuck in the bore, if not stuck completely just kind of sticky pulling the cable back. I would try taking it loose from the carb to see if its working smoothly. You can see here mine was actually stuck took me a minute to get it out, cleaned it up good and no more problems.