Minor update: Curiously, after switching to Sunnoco, the fuel sender is now working perfectly again
What's odd is that someone on here claimed that using Chevron gas and techron fuel cleaner caused the problem whereas it eventually went away with several tank fulls of another brand gas.
So... don't know if this is coincidence, or if for some weird reason our fuel senders are sensitive to something in certain fuels, one of which is Chevron.