Your diligence is commendable, and I sent you an email through this site, but you didn't respond. (You should verify that you have a current email address registered on this site.)

All 02 sensor emission systems require a three-way catalyst to control NOx as does your Mercedes. If the replacement catalyst is really just a "two-way" type, that is the likely cause of your high NOx. I doubt if you needed a new catalyst, but it's too late now unless you saved the original.

You might be able to squeak by with easy timing map modifications that I have outlined in the past and you have apparently found in the archives.

I am willing to discuss your situation and help you out privately, but I no longer regularly post to this discussion board.

Duke