Feedback on Codes / Engine Mis-fire

[M3 Driver]

my 2005 with 85K miles is mis-firing and it seems the number of cylinders impacted is variable. a code scan reveals-

codes
P0302 / P0303 / P0304 / P0305
P0313 / P0316
P0420

i bought an ignition kit from Turner and plan to replace all of the plugs and coils. the valve cover is leaking but i am not planning to address that at this moment but rather get the engine to a place where it is reliable.

i believe that the ignition kit will remedy the other codes. any advice to this end?

[M3 Driver]

the coils and plugs resolved this matter.

[M3 Driver]

i have been enjoying having my M3 now back at full performance. the only negative i have is that it no longer starts/fires with a single crank like it had reliably done for the first 75k miles. it now takes two. i realize that there could be a number of factors. i have never changed the fuel filter at 80K so i will replace it. WHAT ELSE should i evaluate? i should add that i dont believe that this is at all related to the new coils/plugs.