Hey Poppy- I read thru up to page 14, then skipped to the end where you seem to have fixed your problems. I read that you have a Bosch O2 sensor. And also a wideband? I once bought a Bosch but it wouldn't screw into the stock bung so I returned it for an AC/Delco. Did you ever replace that Bosch O2 sensor? Also, I once had an O2 sensor fail at the track and the car wouldn't go much above 50mph as I recall.