What PAhonda suggest regarding finding out how they do the test is a great suggestion.

 

Yeah, the bit about the fans is important.

If they test it under load (on a dynamometer) then they need to provide fans. Engine makes far more waste heat under load than what it does idling. Maybe more heat than the built-in fan can handle. The car needs to be moving through the air.

You won't be able to duplicate that in your driveway. Duplicating the RPM in neutral doesn't do it. Duplicating the RPM in drive, with the wheels off the ground (on jackstands) won't do it either. Under those conditions the engine is probably only making a few HP, because you'll notice it doesn't take much gas-pedal to get the speedometer to read xxx if the wheels are off the ground.

 

Here is another suggestion. Lightly spray the a/c condenser and the radiator with a hose. Don't use too high of pressure, because you may bend the metal fins. Dirt and bugs could build up on there preventing air from flowing through there.

Also, unbolt the radiator and check that no debris is blocking air flow between the radiator and the a/c condenser.

 

Thanks for all the suggestions and advice.
Took radiator to shop for flush/service, carefully reassembled and bled system then replaced the radiator cap with a new one.
The car did not overheat at the inspection station! My guess is that the cap was starting to leak. The new one felt tighter when I put it on.
However, it still failed for high NOx. Perhaps I should start a new thread about this.
Prior to going to the station, I had cleaned the EGR ports according to the excellent instructions from this site. All four EGR ports were egregiously plugged up. New plugs, wires, distributor cap and rotor, PCV valve, and no check engine light. The cat is about 5 years old and is a cheap welded in universal type. The O2 sensor is about 2 years old. The EGR valve is original to the car. In a couple days, I will test the EGR valve and check the O2 sensor. It will be good for me to overcome my VOM testing ignorance.
My mechanic suggested to replace the cat after the car barely passed the last emissions test but said nothing about the ports. So I was hopeful that I wouldn't have to do that when I saw how clogged the ports were.
Again thanks for all the excellent advice.

 

If your unburned HC numbers are good, you might try backing off the spark timing a bit.

More advanced spark = hotter combustion = more NOx & less HC
Less advanced spark = cooler combustion = less NOx & more HC

That is... if the NOx isn't too far out. And of course, your mechanic might be right - your cat might actually be bad.

 

Yes! My mechanic was (as usual) right! It was the catalytic converter. I replaced it with another weld-in and replaced the O2 sensor just for good measure and the emissions were super clean. Nox was 1/10th of the standard. It is sweet to have that up to date sticker on the car. Thanks to all here.