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The high HC and CO indicate you were running way too rich, which was probably due mostly to an old air filter. When HC and CO are high, NOx will drop off because peak combustion temps are down.

You took the correct approach and started with the basics, and that's commendable. All too often we get posts with similar problems and they're off wondering about new cat converters or AMMs or injectors before the simple stuff has been addressed.

Your new CO seems low and NOx is high, which indicates lean running. I suspect you have a vacuum leak somewhere - the usual culprit is the inlet snorkel between the AMM and throttle body. Remove it and look carefully for holes and cracks, and check your other vacuum lines as well.

There's a good chance you may see some improvement with your gas mileage now, with your improved combustion chemistry.
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Thank goodness we don't get all the government we pay for. -- Will Rogers