We need to know what the codes are that are setting it in limp mode. Other wise it could be anything

 

Yea but why with everything unplugged its still broke? It should at least have reverse and forward. Which fails as soon as the trans is running for 1 min.

So that alone tells me it's mechanical. The codes I had b4 were for 02 sensors which I replaced both front 2

 

Yes you must address the mechanical issues first in this case then electrical if indeed there are any.