DTC P0443

[Road Ninja]

i have an 03 Sierra 1500HD with the 6.0. I have a P0443 code coming up. Symptom are very low idle speed sometimes as low as 200RPM, bogs down on little taps on the gas sometimes stalling completely, smelly exhaust and terrible gas mileage. I have replaced the the Throttle Position Sensor, MAF sensor, purge valve, and ran injector cleaner through. When I went to replace the vent valve sel, i noticed there was NO wire harness to plug into the sel.i looked all over for it, inside the plastic wire sleeves all the way to the front door looking for the orange and white wires with no luck. I am completely out of ideas on what to do. Can someone please help!?!

[Nanotech Environmental]

Maybe the issue is on the exaust side? Perhaps you have a wonky O2 sensor or something causing the computer to call for way too much fueling?