I have a fleet of vehicles, and one of them had the same symptoms. It would "hickup" or "lurch" every now and then, but I could not force it to happen (and I tried). After a couple years of this, one day it just died. Towed it to the shop for diagnosis, and it was a bad coil wire from the coil to the distributor. The wire had been grounding out against the air intake system, and the lurch was when the spark hit ground, but, because the symptom was infrequent. As the wire continued to deteriorate, eventually it died. The wire wasn't particularly old, but was abraided by rubbing.
Not saying that's your problem. Just one more idea.
1992 YJ, 401 V8, EFI, TH400, Atlas, D60s, Detroits, Warn 8274, Cage, 37 Krawlers
1997 TJ, 350 V8, EFI, TH400, Atlas 4spd, D60s, Detroits, Warn 12000, Cage, 40 Kevlars
TTC 1994, TTC 2012, Trail Tour participant.