My truck did something like that once. It has always had a "stumble" that was like someone turning the key off and then back on real fast, but one time I was sitting at a stoplight and it just died. Just like you turned off the key. All the guages went out, the radio quit, and it the starter wouldn't crank until I turned the key all the way off and back on. I suspect that it "stumbled" at idle and the transmission drug it down to where it stalled.
I've been back to dodge several times about this and they tell me that the truck is up to date as far as the ECM is concerned and that they can't do anything about it. One idiot even told me that it might be caused by a cell phone from a nearby car, he didn't like it when I told the service manager that it was absurd to me that I couldn't drive my truck around anyone that was using a cell phone without it acting stupid.
Needless to say I am not now nor have I ever been very impressed with the dodge service.
Anyhow, good luck
Mike
<edit> They never have found any codes in my truck when I have taken it back for service.