2002 Concorde 3.5HO
 

This car belongs to an elderly lady in my church, and I'm pretty much at a loss for what to try next. It has an intermittent electrical problem. Occasionally it will start up fine and not have any issues at all, however it will sometimes start up, head down the road and then just cut out and die. The rest of the time it acts like it has a dead battery and will click the starter solenoid and nothing more. I have checked all wiring for corrosion and poor connections, including checking the fuse panel in the engine bay and in the dash. The battery has been replaced in the last month, and I have even gone so far as to replace the ecm with a reman. After replacing the ecm, it started up and ran three times, then cut out again, and will not start. Don't know what else I could possibly try on this thing. Any help is appreciated.

Might be a loose ground wire somewhere. Are there any error codes?

Not receiving any error codes at all, no check engine light coming on or anything. Not until the car stalls out and dies anyway. I did check the connections before when I replaced the battery and had the alternator tested, but will check it over once more and update.