Ford: Vapor lock???, ford club wagon, shelds

Question
Have a 93 Ford Club Wagon, 15 pass, approx. 50,000 miles-not sure of engine size but I believe is largest available. Last year loaned van to take group of kids to camp (steep winding road.) Van broke down on final stretch. Would go about 100 yards then die, sit for 15/20 min., go again about same distance, then die. Took to mechanic next day, (no problems starting and coming downhill) couldn't find anything wrong with it driving it around with computer. No problems all year (drove all over the state of CA, over the grapevine, etc. but no winding steep roads.) This year did the same thing--same place, final mile before reaching camp with my husband driving this time. Friend suggested vapor lock--what causes and is it fixable?

Answer
Vaper lock is caused when fuel lines are getting hot. some times when they get to close to exhaust or ehxaust work has been done and the saftey shelds have been removed or the muffler has been relocated or the exhaust pipes have been rerouted .does the van have rear heat & a.c.?