#1 O2 sensor out, performance went up immediately. on 1996 Toyota Tacoma

What if I don't replace sensor? What should I do about engine light? Truck has 344,000 miles on it.

Asked by for the 1996 Toyota Tacoma
If you have had scanner attached and only has code for that sensor then should be inspected and repaired. It can cause cat conv probs. No explanation about why you feel the performance went up. What do you mean by that?
Hills that I use to downshift to 4th, I can stay in 5th with pedal to spare. Pick-up has also improved. Haven't noticed any change in fuel consumption. Can I remove CAT conv.? County I live in has no emissions inspection. Appreciate the reply. Thank you.
What damage can I do to CAT converter if I don't remove it?