92 KDX200 problem keeping it running

[Railinandnailin]

Hey guys, this is my first post so help me out with specifics.
I have a 92 kdx 200. It sat for most of the winter but when I got it back out it ran great with some new gas. After a few days of it running fine it kept shutting off after a few minutes of riding. I flushed the gas tank, replaced the carburetor with the spare and switched jets (spare carb doesnt leak and was in better condition). My bike is stock so I still have stock jetting. So with that done the bike runs, idles and goes, but only for a short time. Seems that it warms up then shuts down, and will start after a few minutes and repeat the process. What could this be a sign of and what would need to be fixed?

[Mnmonster]

Vacuum in the gas tank maybe? Is your vent hose out of the gas cap clear?