I have a 1995 Yamaha Warrior 350. My problem is when it gets hot (5-10 min of riding) it runs like crap (starts to break up) and then it will stall and won't crank til it cools down. Any info would be much appreciated.
We have put a new air filter, oil filter, oil, and cleaned the carb on it.

 

It sounds like it's running way too lean. You should probably look into re-jetting your carb. The only other thing I can think of is that you're not getting oil circulating, either because you don't have enough oil (which is unlikely but I would definitely double check) or because your oil pump is bad.

Is this a new problem or something that has happened since you had it?

 

could also be valves out of adjustment when they heat up they expand

 

Or your gas tank is not venting properly. If your vent is plugged your tank will starve for air as the fuel is depleted. Once shut down your tank has a chance to equalize. Just for the heck of it, try running with the gas cap off then on and see if this is the issue.