Interesting issue with 99 GT 4EAT

Hello folks, after some deep searching I've yet to find someone with this same issue so I'm posting hoping for some input. I have a 99 Legacy GT 2.5 with the Phase 2 4EAT. Goes into gear great, seems to shift earlier than it should even under load and the odd thing is, when I move the shifter into "1" from a dead stop it will not hold first gear. It acts as of the shifter is in "D" and shifts to 2nd around 2000 rpm. This also happens when downshifting from D to 3,2 or 1. It will not manually downshift no matter how slow I'm going. I'm leaning towards TCM or Range sensor but I'd like some input as I've never seen this issue before.

Thanks.