Ok, like the title says, there are two O2 sensors; one post exhaust manifold, one post catalytic converter and they each have four wires. I discovered this while under my Jeep changing the differential gear oil front and back for some royal purple synthetic 75-90 (got it half off it's normally ridiculous price of 18.99) and my transmission oil and filter (also went to synthetic, but not RP). Hopefully over my next few fuel logs there is some improvement. Can't be too much worse without any towing and running the vehicle for diagnistics for a little while
