Im hopin sombody might be able help me out here.

I took my warrior out ridin with some friends this weekend, Well the place we rode has a river that runs right on it, It has alot of mud holes and shallow backwater to ride in, also alot of wooded trails, Well we started out riding thru the shallow water and mudholes, and my bike was fine and running great, I noticed it got really hot and started spitting and sputtering and cutting off but figured it was because alot of reving with little air moving thru the motor, well we pulled down to a small sand beach on the river and pulled the quads in till the water was over the tires and got off to swim. it sat and cooled in the water for around 45 minutes and ran great until it got really hot again then started doing the sputtering thing again well we went back and swam again and i parked it back in the water, it cooled and ran great again but i never got it hot again so it was fine the rest of the evening, I Have plans for an oil cooler and was wondering if this will solve my problem...... Or if its because its overheating,

Thanks and sorry for the long post.......