you have alot more newer systems than my CJ, but I pulled my hair out for months facing the same thing you are, eventually it went from backfires to stalls a couple minutes down the road. I replaced most of the stuff you did. turned out to be my MSD spark box which wasn't all that old, so I it was the last thing I checked

'80 CJ7; bored 258, weber, MSD, centerforce, rancho 2 1/2 lift, 32" BFG