Troubleshooting a P0300 in N51/N52 engine

[bonez318ti]

I started the car the other day and got a P0306 code while backing out of my driveway and going down the block (minimal throttle) it was running alittle rough and threw a SES code, I went back home. I sat the car for a day and didnt get a chance to look at it until this evening. I reset the code and restarted the car. While warming up, it idles roughly and after a bit, the revs seems to hunt around 700-1000rpm. After a few minutes, I pulled the codes and they were.

P0300, P0306, P0302, B2aaa

The SES light is on, but not the CEL/Engine light. Nothing is blinking (although I havent driven the car since the first day, just started it up.. when I press the ignition button, the car starts right up like usual and is not hard to start ) My TPMS light is on because I recently swapped winter tires that has newer TPMS sensors on it (not compatible with my 128i) but im guesssing this is not related.

When I look up B2aaa, it says its probably because either my OBD2 reader or Torque is not able to interpret the code.

What app can I use to further diagnose this problem? (I only have been using torque lite)

Since it is multiple cylinder misfires, is that something that helps narrow down/out other things for further diagnosing?
The car was driving perfectly prior to parking it and never had a sniff of a rough idle or any CEL or SES/ misfires (Ive only owned the car about 3000 miles and have only done routine oil change, coolant flush, and had the dealer replace a slightly leaking VCG about 1500 miles ago).

For what it is worth, I had refilled the tank with new gas recently with 89 (at BP) - any chance that might have been contaminated and messing with the fuel filter (would this throw a specific code?) Could the gas be the cause of multiple cylinder misfires without any other codes? Would some TEchron fuel injector cleaner be helpful here?

I will try to take the coils/spark plugs out to inspect to see if they are dry, or if there is oil on it on Sun or Mon, however as there are multiple cylinders involved, I suspect it might be something more global also something that suddenly failed as the car was driving perfectly fine previously. ?MAF, O2 sensors, vacuum leak, DISA valve etc - is it correct that these would throw specific codes regarding the sensor or atleast a lean/rich code that would help diagnosis?

Could the recent VCG replacement by dealer have damaged the crankcase vent hose or the valve itself (i saw this as a potential problem for someone troubleshooting a P0300 code they mentioned unplugging the vent hose and 'corking it' to see if it helps the idle, if it does, it might be the valve (im not sure where to disconnect it though, if it is the one on the bank of the valve cover it looks like there is no room there).

Also, is there anything in common with the 2nd and 6th cylinder that might be helpful in diagnosis?

Are there any specific things that I should look at to start diagnosing this multiple misfire problem?

Thanks for any help

[soldierhobo]

I had similar issues, but I also noticed a whine at low rpm. Simple PCV test that 100% diagnosed my issue is, let it idle. Pull the cap. If the cap is hard to open and the whistling goes away. The PCV valve is done (and it's embedded in the Valve cover, the internet provides a kinda way to overcome that).

Also, could be VANOS solenoids. Pull em, clean em, put em back in. Those are things that worked for me. There are plenty of other good ideas out there ;-)