My engine will stall and sometimes start back up but other times it just cranks

I have a 2000 Jetta Gls 2.0 4cyl that stop's running after about 15-20 min then sometimes starts right back up and at other times it has to sit. I took it into a shop they said it was my cooling fans (even though I thought there was only one cooling fan on my car. The fist time it died I was on the interstate. I got towed to a park and ride and I tried to start it it started right up and I drove the last 60 miles I had to go. Then when I was leaving from where I was I went about a half a mile and it quit. Sometimes it would start right back up and at other times it would not. Please tell me you can help. Thank you for you time and consideration.