Rock crawler YJ missing torque at low rpm?

[Red01Z]

A friend has a YJ with a '99 truck ECU, '01 6.0L with an '01 Z06 camshaft in it. I did some minor tuning for him awhile back. He took it to a few events and it runs reasonably well. However, he asked me to take a look at the tune again to see if I could increase torque in the lower RPMs. He said that around 2500 RPMs, the Jeep can barely get out of its own way when it's up an incline and against an obstacle. I'm guessing he needs tire spin and he's not getting it. He has to drop the transfer case into a lower gear and get the RPMs above 3500 to hop over the obstacle.

The ECU came from a company that supplied him with the engine harness. Since the ECU didn't come with the motor, I kept the '99 calibration in it. I'm wondering if the combination of the gearing, weight and tire size might be making the Jeep feel underpowered.

5600 lbs
Stock longblock except for camshaft
TH350 with standard gear ratios (Google says 1st gear should be 2.52)
Stock-ish torque converter
5.13 ring and pinion in a 9" (beefy running gear since it's a rock crawler)
39" tires.. air pressure pretty low

I have much more experience with drag cars. This is a bit of a different animal for me. Since the ECU and engine didn't come from the same vehicle, I'd tend to go down the path of verifying the fuel injectors (and injector data) and start moving over the 01 VE and timing maps and then retuning it from scratch. With or without the MAF, the Jeep seems underpowered to him. Do you guys think being 15% rich before entering PE (and thus making PE rich) is enough to make the Jeep feel underpowered? It's somewhat hard to know if we're making progress without strapping it to a Mustang dyno.

For what it's worth, I had him stand on the throttle on pavement, and the Jeep seemed to scoot as well as my 2015 5.3 Sierra. I'm wondering if he just doesn't need a bigger converter or a shorter 1st gear in the transmission?

joejeep3.hpl
joejeep4.hpt

[MarkusGarvey]

I had the same issue the other day in my Cadillac 3.6 awd SRX Performance, stock tune. I was in a lake bed and I was trying to get up to a ledge and in 1st gear and Had to take a run at it because I have street tires. If the power would stay on i could have got out. It almost felt like my rpm's were limited because of low speed? Did you ever figure this out?