Omegaman,
Thank you for the post. You may have something there. I've read other threads too. My mixture is probably a little rich. I think the catalytic converter is original, looks like it. Based on the NOx it probably is a combination of the c converter and fuel control.
Looks like I've got some work ahead of me on this old beater. I like driving 'das boot' because i have a long commute across downtown Dallas and don't have to worry about wrecking a new car.
I will report what happens with this project, for future reference.....
djb