In the hopes of improved gas mileage, I changed the 02 sensor to a new AC/Delco. At 95k, the original sensor was shot. The tip was coated with black carbon, the sticking EGR valve probably was no help!

Do I have to reset the computer or just drive as normal?

Also, interesting that AC Delco has changed the design of the AFS109. The tip is now a perforated cylinder. The old design was a spiral slotted bulbous shape. I called AC Delco and confirmed that the part I recieved is genuine and of current design.

Just drive it as normal. Besides, there'* no true reset for our PCMs anyway (unless you disconnect the battery).

It will take the PCM time to relearn the new values being sent from the O2 sensor. That will take about a tank of gas before you see any improvements.