My c230 shakes sometimes

Every since i replaced my air filters my car shakes
sometimes and loss of power when taking off. One
day it might run find then the next hour or so it
shakes chk engine is on and it read my coil pack
#3 missfired , my question why does it missfired
sometimes and not all the times or could it be
something else..like for example im driving and
everything is running find then maybe i stop at the
red light then its shakes then i get to my
destination an hour or so im driving again and it all
find then maybe the next day it skakes again or
sometimes it goes a day or two without shaking