The TPS tells the ECU and TCU where the throttle position is at.
If the TPS is really messed up and I mean erratic to a large degree, then it cannot be helping. The thing is a variable resistor with a wiper arm. It is will wear out some day. If it has very small spots of no resistance it will cause a problems.
However, it should prevent the car from going into gear.
The lock-up clutch for the torque converter will not effect the car going into gear or shifting.
Was there a lot of metal filings and clutch/paper in the box when you took it apart?
How did the splines for the clutchs look? These are sometimes called baskets, sometimes they cut if the clutches spin through them.
I have seen some discussion on filling the torque converter after a rebuild but you did not drain yours?
How do you know the selector cable is adjusted correctly?