Chokes out and dies after being hot.

I first brought my Dodge Van 2500 in because it would be hard starting in weather below 40 degrees. After much time, this so-called shop figured it was the "brain", even after changing the coil, dist. Cap and rotor and the ignition coil. The "new" problem now is that they can't figure out that when I drive the van, and the van is hot, the van chokes out and diesels out and dies at stop signs and will not start for ten minutes until "something" cools. I did not have this problem until they worked on the vehicle. They have had my van for two and half weeks! Ridiculous! They can't figure out what's wrong with it. The check engine light has come on once, but of course not now for them. The cold starting problem started last year in winter, but now that is fixed, but now it seems I have this problem. They have let me go from the shop twice and twice I have been broken down after ten minutes of driving it hot, even though I said to run the hell out of it first before they let me go to be stranded again. And again, something is wrong they can't figure out. Help! This is my work van too. Van is in good shape. This shop is ridiculous for not being able to diagnosis this after two weeks. Actually amost all December 08.