First, try to figure out whether you have an actual misfire. This could be
a fuel pressure, crank sensor, EGR, or idle actuator issue.
If you have no trouble code pointing to a specific cylinder, try to focus
on things that would affect all cylinders.
If you can, read the freeze frame data (sensor readings at the time the
codes set) and check your coolant temperature sensor. The engine operates
well on a very narrow fuel mixture range when it's cold. If the coolant
temperature readings are in error, it could cause a misfire.