Any smog experts out there?

I'm probably wrong here but wouldn't a hotter combustion chamber burn the fuel mixture more completely? I agree with changing out the O2 sensor.
You're 100% wrong, and have no idea what NOx is & how it's generated. High COMBUSTION temps create it, & the primary causes are lean conditions or excessive cyl. pressures, but a hot chamber and lot's of carbon can make it easier to occur than normal.