Jeep dies randomly

My 99 grand Cherokee recently died while cruising
down the freeway at 60 (very sneakily; I pushed the
gas pedal and there was just nothing, I was
confused at first about what had happened then
saw my rpm gauge at 0) by the time I got all the
way over with my hazards on I saw the rpm gauge
was registering again and sure enough, pushed the
pedal and took off. Fast forward 4 days and I start
it, idkes normal for twenty seconds and just died
out of the blue. Turned over fine, didn't even
attempt to start. After 15 minutes of heavy prayer, it
fired right up again, and ran flawlessly until it did it
again in the grocery store parking lot. About 5
minutes later it started this time. Yesterday I'm
pulling up to a red light...... dead. By the time I get it
into neutral and turn the key, fired up no problems.
ZERO other symptoms. No shake no shudder, no
alert in ny panel, no key light, no overheating,
battery's good, just RANDOMLY decides to die, in
or out of gear, and eventually (usually pretty quickly)
fires up and runs just like normal. My husband is
"mechanically inclined"  and has replaced a radiotor
hose that was old and flat and gave me new spark
plugs, and checked my grounds.. we Are Stumped!!
I'm the one who commmutes the kids every day, so
I am needing to figure this out ASAP! Anyone have
any ideas??