2nd try: 3-wire O2 sensor.

[Joe Senner]

]What vehicles have  3-wire sensors that are cheap? (make, model, year)?

I picked up a 3 wire sensor at a local auto parts store for $28. it
was for a Ford Mustang w/V8, Ford part number DY-606. works great.

-- 
Joe Senner
WhinerMC#3