All those questions we've been asking you have EVERYTHING to do with test results.
Georgia doesn't show O2 test results? O2 + CO2 are real important to help us determine your air/fuel mixture...I'm surprise they would test for NOx but not O2. Anyways, it's probally the EGR valve or catalytic converter....like SKperformance, I'm too leaning towards the catalytic converter. The catalytic converter is usually the last thing a tech would check...have your EGR checked out first, then have a test and repair station do a catalytic converter efficiency test.
Your test failure probally doesn't have anything to do with fuel, even though you failed for elevated HC (unburned fuel). If fuel related then your CO should rise as well, and NOx should drop down real low because of the richer mixture.
Do you have receipts on what has been done to the car recently?