Toyota Repair: 93 v6 truck engine light, o2 sensor, signal code

Question
I have pulled 2 codes: 21 O2 sensor, and 14 no ignition ref signal.  Cannot reset codes possibly due to ignition ref. signal code?  Truck runs well most of the time, sometimes idles extremely low and other times a little high, occasionally just right.  Friend commented that it sounds like it may have a misfire.  O2 sensor looks obvious, what IS code 14 no ig ref signal?  How do I go about troubleshooting it?

Answer
Code 14 means "no IGF signal from igniter input to the ecm" simplyfied it means the ecm does not recognize that the engine has ignition and there is no spark but if that was the case the engine would not run at all, at this time I would ignore that code and replace the O2 sensor and clear the trouble codes by removing the efi fuse for about 10 seconds.