Dying while driving is a common problem with the 96-98, because of the faulty PCMs that were manufactured for those years.
Some times, although you've replaced the crank sensor, the new sensor could cause problems if you've replaced it with a cheap after market brand.
Defective coil, or secondary ignition (wires, cap, rotor), ASD relay or any of the associated wires from the PCM to the ignition system could cause it. Checking the grounds any all the connector for good contact.
The back firing and serious smell is being caused by the raw fuel (and a lot of it) is still getting injected into the engine and exhaust while the ignition is being lost. You might not get any codes or receive misfire, multiple misfire, o2 codes. It's random.
I blew out a new exhaust system for the same problem.
The above are all the things you should do....., now do this....
and read this...http://www.jeepforum.com/forum/f13/i...8/index27.html