My 1984, CFI 5.0 only seems to have one O2 sensor on the passenger side. Not only that, but the wire was burned through. I think it ran pretty well for having no O2 sensor.
I repaired the wiring for the O2 sensor (it only had one wire) and put the new one in, should I have unhooked the battery for 15 minutes?
If it through a code, it will go away after a few runs. You could unhook the bat. but it's not really necessary.
I should have looked at my O2 sensor a long time ago, I just went from about 15 MPG to 19 on my way into work.