Steve, did you find out anything??? I was also wrong about the O2 sensor, it is a 3 wire unit. This car has a split header that goes into a single 3" where the sensor is mounted. Then into the strangest cat I have ever seen, top mounted single 3" inlet at a 45 degree angle, with dual 2.25" outs. I just ordered the O2 sensor, new injectors, and new valve stem seals to try and get this smoking problem fixed.
Tried to install a new water pump today, and the brilliant engineers designed this motor to where you have to remove the harmonic balancer to replace the pump! Geez...