Replaced MAF, still errors.....

[sparker]

Hi guys,

my car has been running rough lately and all things were pointing towards the MAF going off. Well, last night I replaced the MAF and took the car for a drive. It was not any better, if anything it was worse and even threw a CEL...

I took the car back to the shed and scanned for errors. I got the following:

P0303 - Misfire Cylinder 3 (I did have this one a little while ago, starting to think it could be a coil?)
C2D04 - No further information
B0407 - No further information

Also, while looking at real time values via the OBD2, I noticed that only 3 of the 4 02 channels were giving a voltage (despite this being an Australian model with only 2 oxygen sensors....)

Can anyone suggest I start looking somewhere? I noticed via my wideband sensor that the car was idling and running a bit lean (which also explains the small 'pops' at idle.) I have a few suspects, thinking any of the following: 02 sensor, coil, still a bad MAF or even perhaps a bad cat?

Any suggestions?
Sam