Kawasaki Forums - Help please!

Hi guys and ladies of any ,
I recently bought a 05 ninja 636 from a friend and I have just recently had a problem. The bike runs fine in town and stuff like that. I can go from a dead stop at a light and go full throttle till 120 or so and no problem does great. But if I get on the highway it acts up. After a period of time that I'm running a set speed it starts to bog down and cut off like it has no gas. The gauges will still be on but it throws no fi light. But if I let it sit for a little bit it will crank right up and have no problem unless I get back on the highway again. Can y'all shed any light to what could be wrong??