1985 380SE Emmissions Results

I just took my car to inspection here in New Jersey. There are five ratings, which I have listed below. The NOx reading is high at 1044. What would cause the rating to be so high and how can I lower it?
NOx 1044 HC 17 CO% 0.12 CO2 % 15.1 O2% 0.2
Thanks,
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Your EGR may not be working and/or the engine may be overheating. However, with a reading that high, you may have a problem with the catalytic converter. Check to see if your EGR is working and check your temperature gauge. If those checkout, you will proably need a catalytic converter.
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Thank you for responding. We can rule out over heating, since the engine is not over heating. although I did change the thermostat. About two years ago the NOx was 950, and it is now 1044 and getting worse.
Any idea how I could test the EGR or catalytic converter?
Writes:

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You will need a hand operated vacuum pump. Disconnect the vacuum line at the EGR and plug it. Attach the vacuum pump to the EGR. At idle when you pull a vacuum, the idle speed should drop noticeably and increase again when you release the vacuum. If no change in idle speed the EGR valve is bad.
Peter

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You should be able to test the EGR valve for leaks if you have a vacuum hand pump with a gauge. The EGR lowers NOx by recirculating exhaust gas with intake air. This lowers combustion temperatures and pressures and should lower your NOx. I understand that you can test your catalytic converter by measuring it's operating temperature with an infrared thermometer. I've never attempted this but you might speak to a shop. Since you are in New Jersey, you might contact Bill Ditmire who has a Mercedes shop in New Jersey. He knows a lot and is
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