vapor lock

Out on the road, just wait for it to cool off. When you get home, order one of these and plumb it in.

http://cgi.ebay.com/ebaymotors/Mopar-Hemi-440-426-Fuel-Filter-Vapor-Separator-YEAR-ONE-/130410413025

That will fix it. It will help even more if you move any fuel lines away from being close to a high heat source.