Transmission question

Unless you have a manual valve body the TP cable or linkage is eveything to the shifts.
It's what tells the trans how hard to shift and when.

Try tying it halfway back down at the trans and see what happens. :-)
You'll believe it then for sure.

It has been said here a hundred times that it is really bad for a non manual valvebody trans to not have it hooked up and working right, so I won't say it again.