HI All,
I know this is an old post, but I just wanted to added an easy fix to the P0301 symptoms. I just got my xf smogged, and after I got the paperwork from the technician, I started the car, the check engine light came on, and I had a loss of power. I drove it home (2 miles), and checked the code - P0300 and P0301. Erased the codes, but they popped back up as soon as I started the car. After researching P0301, I opened up the hood, removed the cowl, and was proceeding on swapping the ignition coil from cylinder 1 to cylinder 4. I started to unclip the connector from the cylinder 1 ignition coil, when it just came out with very little force. Clipped it back in, put cowl back on, car started and ran fine. Erased the codes, and no codes reappeared. So, before spending a ton of money, check the ignition coil connections. Not sure why my connector fell out, but maybe the smog technician inadvertently pulled on it while doing the visual engine check.
-Jerry