Juan,
I concur with all the above comments and advive so no sense repeating. EGR is the major contributer to reducing nitrous oxides and nitrogen dioxides, so be sure the system is funtioning. Apply vacuum to the valve at idle and make the engine run rough or die. Then hook it all up and observe that the EGR needle moves as you race the engine. You can tweak CO up a bit and that will also help. If you have an air pump, it plays a minor part, so make sure it works. Also be sure you are using the grade of fuel the car calls for. If the car calls for premium, combustion temps will increase with faster burning lower grades. All in all I thought those readings were good across the board and NOX isn't that far off. In fact I had a 90 300SEL in the same boat last month and tweaking the CO up got it through.

Good luck,
Peter

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