Hi all just joined this forum and looking forward to reading a lot about the 986's on here, I'm from the UK and after seeing a lot of threads on codes for the 986, mine is throwing up some random ones, I have had new maf (not bosch), new bosch 02 sensors, new coil packs and plugs (just brought some beru ones to replace as ones I put in weren't iridium) and having a nightmare trying to find the cause of a random misfire codes are p300, p301, p302, p303 and also this one I have never seen before p1340, and this one only reared its head the other night, they are intermittent codes and can go weeks without showing but have shown twice in the last week but the p1340 code only once (since cleared never been back) codes this evening were multiple misfire cylinder 1, 2 and 3, engine changes tone when oil filler cap removed and does again when vacuum pipe removed, smoke test being done asap, I am running out of ideas, going to do a live scan of 02 sensors tomorrow night and make sure they are doing their job, any ideas are welcome as need to drive the car but don't want to risk any damage, I am thinking start with good spark plugs and worse case scenario injectors fingers crossed


Original pic with p1340 code showing

 

Interesting that you are having problems with only bank1 misfires. That makes me think you have a problem with the wiring harness.
Not sure about the O2 sensors, but the way your oil cap is acting makes me think you have a vacuum (AOS) problem.