Wideband O2 sensor ("shoulda bought this years ago")

^ I think your onto something, ESPECIALLY if it has a tall duration. Balancing drive-ability, and getting all the circuits to stack right and act as one smooth operation from idle, cruise, enrichment, WOT is a juggling act, sometimes you have to compromise..... Then the weather changes; all you can do is get it close over an average then take the distraction out of the car.