My 74 460 truck did that when it was hot enough out to need the a/c. Ford had changed about everything on it except the box. One day when it quit I was in front of a liquor store, I went inside, got a bag of ice, laid on the box and in 2 minutes it would start and run----replaced box and no more troubles---

funny this post came up---I just ran across that box cleaning out bottom drawer of a cabinet today---