if you're running OBD1 there is no second O2 sensor. the second O2 harness would be on the chassis since the rear one is further back after the cat.
which ECU are you running? chipped?
are you setting a CEL?
are you running an OEM cat or high flow?
are you running cam gears? set them to zero or swap in your stock ones makes a HUGE difference to emissions.
check my site for VX swap wiring help.