Misfire codes on Bank1/Bank 1 too rich

[conkyd]

Hi all,
Recently had an error code for the bank1 sensor1 o2 sensor (pre cat I believe). Car ran full throttle fine (open loop fuelling) but jerky and lumpy at idle and light throttle. Replaced the o2 sensor (B1S1). The fault code cleared and it was better, now intermittently throws Cyl 1,3 and 5 misfire (Bank 1 I believe). From research I thought the rear o2 sensor (post cat) may have been the issue so I changed it out also. Car is better but still a little jerky on light loads and idles rough/lumpy. Thought maybe I had fouled the plugs so swapped them for new ones (needed them soon anyway).
Looking at the live datastream I can see B1S1 and B2S1 have equivalent voltages but the post cat sensors B1S2 and B2S2 are way off. The post cat sensor is not reading correctly. I will swap the S2 across banks on the weekend to check and further diagnose. If that doesnt change where the misfire is i will swap a coil pack but it is unlikely for all 3 to crap out at the same time?

Wondering if anyone else here has had something similar. I have searched through the posts but others had misfire issues all the time. Mine is only doing it during closed loop fuelling. Any thoughts?
Thanks in advance.

[Yowie]

If you have a MAF sensor (eg hot-wire style in the air box) give that a clean with the MAF Sensor spray and see how you go.

My wife's 2009 Forester had similar symptoms (ended up running really rough and throwing a bunch of unburned fuel out the back as smoke) just because the MAF was dirty.

If it turns out not to be your problem, at least it's a cheap attempted fix.

[conkyd]

thanks Yowie, Great idea and I forgot to add that I had done that. Did the upper cylinder cleaner and a new air filter whilst I was at it.