I had a Chrysler Concorde that was doing the same thing. It would just cut driving down the road. Sometimes if I was stopped the engine would quit but start right back up. The dealer said the transmission code showed something wrong with the transmission but they said they couldn't find anything. About the time I thought I had it figured out some guy needed transportation and wanted to buy. So I sold it to him and told him what the problem was. After much research I believe that it was a loose or bad ground connection.

 

That's what I'm thinking and where it is who knows. Time to start pulling on wires.