Had codes read for my 08 MCS since it's been acting oddly with a solid yellow CEL on the dash (nothing on the tach). Stuttering when accelerating hard, throttle not as responsive as it used to be, a knocking noise when I take the engine by surprise between 1400-2200rpm, and white smoke when the engine is warm when I remove the oil cap. 101k miles, oil burn smell, and the only thing that's still covered under warranty is the HPFP.
I should also note that when the knocking occurs, I can see what appears to be white smoke coming from the tailpipe.

The codes that were read are below, and I know that my post-cat sensor needs replacement (I ordered it not long ago, but now that I look at it again I might need a new pre-cat as well unless there's a leak I don't know about), but everything else I'm not sure about since I did have the spark plugs and ignition coils replaced.

Any idea what could cause the misfires?

 

You don't say what maintenance you've done/had done on this vehicle. I had a P0300 and P0304 code recently, right before I had planned on doing a carbon blast on my '09 MCS. I blasted the valves (you can have the dealership do it for about $600 if you don't want to DIY), and I changed the spark plugs. This at 60K miles. I cleared the codes before starting her back up, and have had no problems since. I couldn't say what your problem is, but if you haven't cleaned the valves, it's a good place to start if you can do the work yourself.

 

^^^