Kratatat

So I'm at a loss with my '99 xj and figured I'd reach out on here, in hopes that someone might have an answer or similar experience.
about a few months ago, my CEL came on throwing a po700 code.
naturally, I was directed towards replacing the nss. However, this didnt fix my problem.
my next move was to replace the TCM under a friends suggestion that it could be miscommunicating with the main computer, but the CEL still persists.
A friend of mine then pointed me in the direction of looking into faulty wiring and the nss connector. We found a small amount of resistance in one and worked to replace it (going to the tcm), however upon doing so the jeep would not start. My guess is that the wire must splice down elsewhere. I was going to see if alldata had some sort of diagram for me to follow for that, but I'm still doubtful that that's my issue.
I need to pass inspection and am hoping to find a solution here.
Otherwise, the nss seems to be working properly. I'm only able to start in the appropriate gear and my reverse lights come on when in reverse. I've even visited a transmission specialist and asked them what they thought. Even they agree that the tranny is performing properly and said I did everything they would've tried to troubleshoot the issue.
so yeah, I'm stumped!