Stalling issues at warm up. Engine dies and won't restart until cooled.

I'm going to investigate the vacuum idea ASAP... Had a co-worker that claims he heard a leak the last time I started it. Could be the "smokin' gun"... I also forgot to mention one other important "symptom" of this on going problem. At first start cold, trans would also not shift until higher than normal revs until the enginge was shut off and restarted. That was just prior to the stall problem occuring. It would idle high until warm and not shift correctly. After turning it off and restarting, it ran fine. Thanks for the input/reply!!! Will keep posted on progress.