Who was trying to tune your Paxton? The tuner who did my truck had all the same specs for my PCM as LX platform had. Being an 03 you might have had a few things locked out but my 04 PCM pulled up the same tables and adjustments the SRT Jeep did with the stroker.
Well, most of the problem I think is the 03 PCM, the trans would go into "loop" mod, shifts would hang, truck would stall on fast stops, could not get the A/F were it needed to be. I was having to get the truck retune every 6-7 weeks, it was like the PCM was setting everything back to stock settings. The best I ever got at of the truck was 13.6 S/C ....cut my lost and went N2O 13.1 - 12.9.