It's been a few months since I updated and since January, I have done the following:
Replaced most of the coolant lines, installed DSMlink, replaced the water pump, installed a new timing belt, installed new O2 housing, new O2 sensor, new battery tie-down, replaced the valve cover & installed new VC gaskets, found a stock oil return line & installed it. toybreaker reminded me to check the oil cooler bolt and when I touched it, the damn thing wasn't even finger tight. I have no clue how the car made it back from TX without dumping all the oil on the road. Bought a new O-ring for it and threw some blue lock-tite on it and torqued back down to 31ft-lbs.
She was all back together and I decided it was time to start her up this past weekend. She fired up ok, but for some reason, my O2 sensor only cycles some of the time. Sometimes it doesn't cycle at idle and other times it does. It seems so random. Yesterday, I started it up and the O2 cycled just fine for a couple minutes and then it just stopped cycling and remained at 0.02 volts. I idled the car until it was up to temp figuring that the O2 would maybe start up again...But nope. So I shut the car off, waited 1 minute and started it back up and the O2 cycled again for another few minutes and then stopped cycling once again and went back to 0.02 volts.
So at this point, I'm thinking that there is either a short somewhere, or there's a gigantic exhaust leak. My only other idea is that using an Ebay stainless O2 housing was not a good idea. Any other ideas?
Oh, BTW - the awful noise that only happened after 3500RPM was the rear balance shaft. It was 360 degrees out. When I did the timing belt, I fixed that and the car runs just fine all the way up to 4000RPM, which is as high as I've taken it so far.