Well, I have had the new sensor installed for about two months, and I have run a couple full tanks through it, and I am now averaging between 13-15 mpg, which is much better than the 8-10 I was getting before the O2 sensor.
Huge thanks to all who gave their input, and to Jerry for recommending the NTK sensors through Rock Auto. They were almost half the cost of the Bosch ones at AutoZone, and I liked the idea of keeping it OEM. (BTW, the faulty sensor that I took off and the PO replaced just last summer was in fact a Bosch sensor. Will not be buying Bosch in the future).
I will keep subscribed to this thread to offer any help to anyone else, and giving any necessary updates. Thanks for all the help. WF has been the best place for all the help I need.