Preventing stall while crawling.

I had a JK Jeep Rubicon back in 2007 with the 6 speed manual and one of the coolest things about that rig was the fact that it would go anywhere. Even more impressive was that in 4Lo and first gear you couldn't kill the thing it would just lump along all the way down to 2-300 rpm with no foot on the gas up hill and down hill it seemed to engine brake itself and maintain that super slow crawl speed not allowing itself to gain momentum with gravity. Was truly a remarkable machine and I would love to.duplicate that behavior if possible in the 5.3 LS 1976 GMC I am currently building. I have no clue if it.is doable or even where to.think about starting to make changes in the tune to achieve this. Anyone got any ideas?

Idle speed, throttle follower, throttle cracker would be a good place to start. First setup your minimum idle speed/TP Voltage.