Thanks again for the input. I figured I'd need the head bolts, but not the rocker arm bolts. I got the second O2 sensor done last night. I thought they would have been about an hour job because I'm slow. I figured, how hard can it be? Unplug the sensor, unscrew it, screw new sensor in, plug it in. The rear sensor'* heat sheild cover was buttoned up by the people who did my CAT with a fastener that does not want to come off- took me 40 minutes just to break them free (destroyed the fasteners). They were good and probably will hold the firewall up, but they were not good for the sheild over this wire since it'* serviceable.
Then the front. Wow. I heat cycled it about 3 times, sprayed it with PB. I was using a box wrench on the end of my socket and putting all my weight into it (250 pounds- but that'* a seperate issue). Nothing was working. I finally ran out of PB and all I had was some T-9, which I wasn't sure I should be using for this. I sprayed it down anyway because I was fed up and it was a last ditch effort for the night. (I had been trying, failing, driving it around and doing other things, trying, failing all day). I left for about 15 minutes to do some other things- came back and it came out like it was never tight at all. And that was cold. At that point i didn't really care if I should have been using the T-9 or not, but I made sure to wipe off as much as I could.
I also checked my coil packs, but not the wires yet:
1-4 Primary = .42 Secondary = 5.679
2-5 Primary = .43 Secondary = 5.667
3-6 Primary = .43 Secondary = 5.868
Seems good to me, but a bit low on the primary. I'm guessing a slightly lower resistance on these things is actually a good thing (means more spark can flow, right)? Plus the MSDs are lower- and these actually seem to be in spec with those or better. Not bad at 150,000 miles almost.
I will check the wires today, I dread removing the rear wires though....
Oh yeah- and the CAT was changed out about 2 months ago. I haven't had a lot of time to work on my car, so I'm just getting to this stuff now. Even at that, the mileage went up 0.1 mpg yesterday with just a new rear O2. Probably a fluke, I understand the logic and what you're saying....I just found it curious. The old O2 was in ROUGH shape (dented, carbon).