General Maintenance & Repairs - 2002 WS6 misfire and knock

Hey everyone. I have an 2002 collectors edition WS6 with 101,000 miles on it. I know way more than I ever wanted on her. I have had no major problems out of the car besides replaceing everything that goes to the clutch until now. Two weeks ago when I went to start it in the morning it back fired really loudly and locked the motor up for about 30 mins or so. I finally got it to kick back over and it ran fine. No skipping and lots of power. Sunday I went to go get some food before pool and when it started up it knocked loudly. Good oil pressure. I did not drive the car Saturday at all. The car is still knocking and throwing P0300 Random Misfire Code. The engine rocks badly and you can tell it skipping. Just changed the plugs in it with AC Delco plugs. Oil pressure still holds good. No fluctuions. Has anyone ran into this type of problems? Could it be a bad lifter? Bad rocker? bad seconday air pump? Any ideas would be helpful. Oh yeah the car has only had mobile 1 and a K&N oil filter on it since I got the car with 15,000 miles on it. Thank you and I would appreciate any and all help.

I would drain the oil and check it carefully for needle bearings or pieces of metal. It could be a lot of things, lifter, broken ring, spun bearing. See if the oil tells you anything.