code read 173 running rich, i changed o2 sensor, still rich, what else can be done, appreciate any advice. 93' 4.9L

 

The 173 code indicates that the O2 sensor is not switching from open to closed loop. That doesn't always mean the O2 sensor is bad.

Has the thermastat been changed or your water/coolant level low? Too low of temp thermastat could effect it. The water temp sensor for the computer (not the one that goes to the instrument panel) could be bad.

Does your engine have a air intake temp sensor or a mass air flow sensor?