300E Smog Emissions Test Results

Hi
I have a 1987 300E live in California, however the car is from the east coast, so it is a 49 state car.
I am up for my smog / emissions test in a couple of months.
The NO have been high the last two tests. And am afraid that they might be even higher and fail the upcoming tests.
Here are the results of the last two tests. Any ideas of areas that I should look into would be a great help.
Thanks
2004 Test 15mph 2602 rpm %CO2 15.0
%O2 0.1
HC MaX 110 HC AVE 31 HC MEAS 62
CO MAX 0.71 CO AVE 0.10 CO MEAS 0.24
NO MAX 772 NO AVE 237 NO MEAS 768
25mph 1726 rpm %CO2 15.0
%O2 0.1
HC MaX 85 HC AVE 20 HC MEAS 35
CO MAX 0.59 CO AVE 0.09 CO MEAS 0.12
NO MAX 711 NO AVE 199 NO MEAS 303
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2006 Test 15mph 1735 rpm %CO2 14.4
%O2 0.9
HC MaX 110 HC AVE 31 HC MEAS 104
CO MAX 0.71 CO AVE 0.10 CO MEAS 0.20
NO MAX 772 NO AVE 237 NO MEAS 765
25mph 1729 rpm %CO2 14.4
%O2 0.4
HC MaX 85 HC AVE 20 HC MEAS 63
CO MAX 0.59 CO AVE 0.09 CO MEAS 0.16
NO MAX 711 NO AVE 199 NO MEAS 356
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Make sure you change oil before the emission test.
Add dry gas to fuel tank to lower the emission.
You probably can lean out the fuel mixture a bit more, but not much before your engine idles rough.
If all above failed, then you need new cat converter.
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Right, the catalytic converter is supposed to reduce NO contents. High NO contents is then due to ineffective catalytic converter.
As said, you can cheat at little by leaning the mixture, but that would lead to a higher HC contents. But still you may just pass one more time.
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