Car has problems when it's too hot.?

The other day it was 120 degrees outside and my car started to have problems. I had my car in cruise control all of a sudden it started slowing down, I would push on the gas peddle and nothing would happen, so I lightly pushed on the gas peddle a few times until it grabbed and sped up. But then it would only slow back down and again I had to push on the gas peddle till it grabbed. Finally i pulled over and it turned itself off. What could cause this? And also if I let my car idle for more than 30 min or so then try to drive it, it turns itself off. People have said it could be vapor lock but I have an 04 Volkswagon Bettle and other people said its too new of a car to have that problem. Can anyone help me???