buy a new o2 censor since its shooting that code off. Second if you think the cat is burnt out and does not work anymore you can A) keep it and gut it and use it as a straight pipe while you buy another new cat or B) buy another cat but yeah definetly buy a cat while your getting a new o2 sensor.
www.pdm-racing.com has the stuff you need. Also check if you need a tune up , you know clean filter,new oil,new plugs, wires etc etc.
Other than that reseting the ecu doesnt actually help cause the codes will show up again. The irratic idling btw has to do with many things one being the o2 sensor.
So do some research about the sensors and smog and you should be alright.