[b][/b] 97 Ram1500 convertor not locking and not shifting into 4th.

Torque Converter Clutch is what the codes point to. For future reference the code is p zero not p o.It makes a difference when looking them up. This might help. https://www.youtube.com/watch?v=X9fIKys_9SI

Both of those functions are performed by electronically controlled solenoids.

There was a wire corrosion problem between the trans relay and the solenoid plug. Pull the plug at the trans and check to see if one terminal has 12 volts, and one terminal has 5 volts. (which terminals have which voltage depends on the year). If the 12 volts are missing, that power comes from the relay, if the 5 volts are missing, that comes from the ECM. The bad wire splice is near the top of the trans on the wires going to the solenoid plug, at the firewall.