Intermittent Misfire

[The Flying Ox]

Hi

My new(ish) IS200 has developed an intermittent misfire. It drives absolutely fine 99% of the time, but occasionally it feels a bit sluggish when accelerating. It goes back to normal after about 10 seconds and that's generally it.

I've checked for codes and have the following:

P0300 - random/multiple cylinder misfire detected

P0301 - cylinder 1 misfire

P0302 - cylinder 2 misfire

P0303 - cylinder 3 misfire

P0304 - cylinder 4 misfire

P0305 - cylinder 5 misfire

P0171 - system too lean (bank 1)

Also these, but they only show up if I do a code check with the ignition on but engine off, so I'm assuming it's due to slightly less juice from the battery:

P0003 - fuel volume regulator control circuit low

P0143 - O2 sensor circuit low voltage (bank 1 sensor 3)

I've had stuff before (on the wife's old Ka) where the codes don't necessarily point to the underlying cause of the issues, and it became an expensive lesson in trial & error working out what was the culprit. So, before I go all nuclear on my bank card and start buying coil packs, spark plugs, O2 sensors, fuel pumps, all that jazz, does any of the above point to one thing in particular?

Thanks in advance.