I've got a 1991 4.0 HO with a 5speed. If I put it in any other gear it runs just fine, if I try to back up the jeep just dies an shuts down

 

I guess you'll have to figure out whether the problem is electrical or mechanical.

Electrically everything should be fused. I'd think something that's dropping enough amps to ground to kill the electrical system would blow a fuse (though I suppose the PO could have bypassed the fuse).

Do the dome lights/headlights flash or dim down when you put it in R?

 

One of my employees has a 97' grand cherokee and his is an automatic, but his started doing the same thing since its turned colder and his was a bad battery. But it would be slow on starting, but would start, and when he put it in reverse it would die. Sounds weird I know, but a new battery fixed it.

 

There was a guy on another forum that had that problem and it turned out his bell housing to engine bolts were loose.

 

Does it happen going from both park to reverse and from drive to reverse?...I heard a dirty IAC could cause this to...