Hello , Im pulling 2 codes from my 1996 850R . One of them is calling for a misfire on cylinder 1. Im assuming a regular tuneup ( plugs, plug wires ) would take care of this, the car drives extremely well. I was told when I bought the car it had a bad 02 sensor that is why the light was on. The 2nd code is Main catalyst efficiency below threshold ( bank 1 ) and I am assuming that this is the upstream 02 sensor right off the turbo. Im very familiar with RWD but FWD is new to me and Just thought I would ask if any of you have dealt with this.