We recently purchased a 1999 Ram Sport w/5.9 to use around town.
We took a chance on this one, because it will periodically die when cruising along in town or on highway (Lower highway speeds, anyways) and we got it for a good deal knowing this.
If she drives a bit of distance through town, it does it to my wife constantly, but if she is patient, it will eventually restart. One session it died a ton of times while she tried to go a mere 6 miles through town. Now she won't go more than across the creek to take the kids to the bus. (Three miles each way twice a day.)
It has died on me one time, when I was pulling up to a stop sign at the farthest end of town after driving approx twenty miles. (Of course there were 20 cars behind me!) I started to accelerate to move up a bit and it shut clean off. No change in the odometer (I heard this could happen) and all dash lights normal.
All I could check was whether it had rail pressure, and it shot fuel clean across the fender when I depressed the schrader. It acted as though no spark at all. I felt around for excessively warm or hot components, (Coil, relays, ECM, etc.) but found nothing odd. I simply had no tools with me.
I tried a few times to start it, and unplugged the ECM connectors for a moment, got back in it and it fired off. Drove it home 11 miles with no more trouble at all. The dealer who sold it to us had put a new ECM, Oxygen sensors, a coil, cap and rotor into it to try and remedy the issue, to no avail.
I am asking if this sounds familiar before I try using a scan tool to record various components when (If) it dies again. Anyone seen this?