HC and CO are very good for a M103. Zero O2 means the catalyst was working at high efficiency. The high NOx may mean an EGR problem. You need to do a thorough functional check of the EGR system. Even if it is not working, judicious diddling to the ignition map should lower NOx. My car was low double digit NOx, and it doesn't even have EGR.

Read the following thread and the threads it links to:

http://www.peachparts.com/shopforum/tech-help/117048-successful-ca-asm-emission-test-ke-fuel-system.html#post833484

I hope the "Bosch plugs" are H9DC. That is the ONLY Bosch plug that is correct.

One question: What was the cause of your "faulty" check engine light? Did it yield an EGR code?

Duke