[Formulajones]

A lot of guys do run and/or recommend the 02 extender.

I've never tried one or found the need to. I guess they help keep the 02 a bit cleaner? My 02's also look black but they've still worked fine for years. I see it as pretty normal fair considering it's stuck in an exhaust stream. I've never seen one burn crystal clean, even in a factory EFI vehicle.

Best to check the learn table though as faulty 02 readings usually corrupts the table and causes other issues.

Could be a few reasons for repeat 02 failure. Chris at EFI System Pro has a good breakdown of reasons. He also has the Sniper and Terminator X 02 sensors on sale right now 10% off and he's in your neck of the woods.