What are definite possible reasons why my car would fail emissions?
My car used to fail both low and high idle speeds by emitting high NOx and HC levels. I did some basic tune up things like:
-oil & filter change
-air filter change/cleaning
-cleaned all vacuum lines
-clean throttle body
-attempt to clean the AIV with carb cleaner
-attempt to clean the EGR with carb cleaner
-changed spark plugs to OEM Plugs from dealership
After all this tuning, and the use of "Berryman's Emissions Pass" fuel additive (which claims to reduce both NOx and HC levels at any idle), my car still failed emissions with both high NOx and HC levels at high idle. Half solved. The mechanic there said that replacement of the EGR valve and catalytic converter may be needed, or even "advancement of timing". (?) These are my LAST resorts! What else should I look at???
I'm stuck! I'd appreciate ANY helpful hints!!! Thanks!
Emissions failure
on the word emissions I found 
Linear Mode
