From what I've learned, mistake #1 was installing a trans-go kit. I think you might be hosed right there. Is there any way to remove the "kit" and return the VB
back to stock to see if the issue goes away, or did you drill the sep. plate for that kit? I'm only familiar w/ the j-mod since it seems to be the only shift modifier that works w/ the 4R.
These are highly engineered precision vehicles, the first step in diagnosing the problem is to strike the suspected offending part sharply and repeatedly with a blunt object, then re-test.