DTC's Please! someone help me
 

Hey Y'all,
I'm a newbie to this forum and I own a 1998 Honda Accord Ex vtec and I got problems!.. I went to "inspection" N.C. and I failed. My Honda runs like a scallded dog but lately it seems to be going through a shit load of gas. My check engine light came on so I scanned it with my OBDII scanner. So far the following are the codes that I got.
PO420- Catalyst System Efficiencey Below Threshold(Bank1)
PO301- Cylinder 1 Misfire Detected
PO302- Cylinder 2 Misfire Detected
PO303- Cylinder 3 Misfire Detected
PO304- Cylinder 4 Misfire Detected
PO300- Random/Multiple Cylinder Misfire Detected and finally,
P1259- VTEC System Circuit Fault (Bank1)

I figured that since I'm really burning a lot of gas that my O2 sensors might be failing and the computer is screwing up. Maybe it is putting a phony value in to replace the o2 sensor readings. I also figured that the misfires could be plugs and wires. I'm not sure. If I just replace what the codes indicate is wrong I could spend a small fortune.... Catalytic Converter, O2 sensors, plugs wires, rotor etc.... What would you troublshoot first?

You need to invest some time in the search button, all those DTCs have been posted. Follow the Honda procedures and find the common link.