Oxygen sensor 97 E420
 

CEL comes on today. Idle vibrates, seems to be intermittent miss fire, not smooth as yesterday. There is some Surfur smell when I park the car in the garage.
Hook up the code reader and got the following as sequenced by the reader:
P0300 (miss fire)
P0301
P0304
P0303
P0302
P0305
P0307
P0130 (Oxygen sensor Circuit Malfunction (Bank 1 Sensor 1))
P0135 (Oxygen sensor Heater Circuit Malfunction (Bank 1 Sensor 1))

The car has approx. 136K miles and both O2 sensor plugs showed date code 1997.
I'm going to change both bank1 & bank2 O2 sensors.

By the way, the ignition coils were replaced around 100K miles.
I'm wondering why there are so many miss fire codes which are not limited to the bank1 cylinders?
And the problem comes on suddenly.

Faulty fuel pressure regulator? Other possible causes?