You can check your o2 sensors at the same terminal you used to check the codes.
Put a volt meter on DC volts and check the voltages at OX1 (first o2 sensor) and TE1 (ground)
Your rear o2 sensor OX2 should not sweep that much since it is behind the cat. converter
Is the 1993 a OB1His '94 is OBD1 and you can simply use the paperclip method to jumper terminals TE1 and E1 located on the black "Diagnostics" box on the passenger side under the hood. Turn the ignition to ON and read the blinks. There should be several posts that go into more detail on this but that's the quick version.
More information here: Troublcodes.net Trouble Codes OBD & OBD2 Trouble Codes and Technical info & Tool Store. By BAT Auto Technical