So my 08 63 has been doing this thing where it will start to misfire, throw a check engine light, and then be perfectly fine when I turn the car off and back on. It usually more than a month between issues and usually only after having the throttle to the floor for a couple of seconds. I kept my scan tool in the car and when it did it again I was able to get a code P0304 for the #4 cylinder misfire. The spark plugs have 16k on them. Does this happen a lot to this motor? I have only owned the car for 19 months.

 

No, this isn't a usual thing for the M156 engine. Have you diagnosed your issue, and what does the code actually say is wrong?
I've owned two E63's and one C63 with the M156 engine, and only had one CEL, do to a bad gas pedal throttle sensor at WOT.
But never for cylinder misfires.

 

Which code does it show? You may want to stop by a indy shop and have the car scanned. The codes are stored in xentry so you will be able to see what hit. The M156 will go out of time, but even mine was off and showed no codes for it, also I have heard they have vacuum issues and tons of oil gets ingested into the intake, mine had a half a cup of oil inside. Pulling the spark plugs will tell you a lot.

 

 

I had a coil pack go bad on cylinder 6. It was about a $60 or less & 15 minute fix. So they do occasionally go bad. Its a good time too clean your filters too