97 Cadillac Deville (Service Engine

My car is idling rough and the Service Engine light blinks on/off continuously. I ran the codes and they are P0301, P0401 and P1258. Does anybody know what this could be? I changed the plugs, wires and ignition coils about a year ago. Catalytic converter was replaced around the same time but the O2 sensors hasn't been changed. Could that be the cause?

301 is a percieved engine miss in #1 cyl. Google the other two for in depth info, plenty of info out there.