Van won't start after getting to temp til it cools down again

What is your question?

My Pontiac Montana 03 will start and run til it gets to temp. As soon as I shut it off, I have to wait about an hour before it will start again. Sometimes when I start it I smell gas but not every time. Have taken it to 3 different mechanics in town and they can't find anything wrong with it. Could you please help?

How long has your 2003 Pontiac Montana had this problem?

6 months but vehicle not used