I ran down the mental list, only the valve cover gasket was replaced and I didn't use any sealant. Sensor was a bosch and didn't require splicing
a different plug to match the socket. It was a match straight out of the box. No work on the harness either. I guess I'll just break down and buy a new O2 sensor. I did use a carb spray to clean out the throttle plates.
Said it was safe for O2 on the can, but maybe some of the crud that came off the plates wasn't. Problem didn't show up until weeks after though. Funny thing is the code is intermittent. Mostly happens on extended hi-way driving when the trottle is held steady. I was mostly curious about the function of the O2 sensor. I'm assuming that with only one wire, that the signal is voltage to ground so a bad ground at the threads or the wye pipe would read the same as a bad sensor? I'm guessing. Thanks for the feedback though. I'll go over the harness and connections again.