I passed everything except NOx. Legal limit is 3.5 - I had a 3.57.

Any tips on getting this down .07? This is getting ridiculous, I have replaced just about everything on the list of things to replace. Just need a quick tip to get this thing through. Any help would be appreciated!

Have you tried isoprophyl alcohol (heet) in tank?? Seems to help nox. Have you tried retarding base timing a few degrees?

An EGR is used for reducing NOx by recirculating exhaust and ultimately lowering combustion temps.

Has is been replaced? Do you have any codes stored? Try tapping it with the engine running, it may brake any carbon loose. Also, try some upper intake cleaner along with cleaning your throttle plate. The less carbon buildup, the less likely your EGR is to get stuck closed.

http://www.crcindustries.com/ei/cont...x?PN=05063&S=N

pick up a bottle and follow the directions,you will be all set.

Lucas Octane Booster help me pass when my car barely fail too. It only cost $10.
Make sure your timing is set at 6 degrees.

Agreed with Vincent- make sure the initial advance is set at stock or even slightly retarded from stock spec. High NOx is caused by high combustion temps. Advancing the ignition timing a bit is great for power and efficiency but also raises the NOx readings considerably.

Set it back to where it runs best after you pass the sniffer and get it back home.