I recently had my egr valve tested and cleaned and told it was ok. I also had my catalytic converter changed aswell... My emissions had great numbers on all test except the Nox on 20/15 which was over by 700. My check engine light is not on, but my car does get bad gas mileage. It's a 4cyl v-tec. Oh and the muffler is relatively new.

 

Most likely your EGR ports are clogged.

 

car overheating? check ignition timing and try sea foam