Ford Focus has an irratic idle and miss, could this be caused by a bad coil pack?

Start by checking for vacuum leaks and check the IAC.

BEFORE you replace any parts, TRY switching spark plug #2 with another cylinder, or fuel injector, or spark plug wire. See if the misfire "follows" the switched part. If that fails, you could have a vacuum leak near cylinder #2, but I doubt it. If the above tests fail, your problem is mechanical (broken valve spring, collapsed lifter, improperly seated valve etc.).
May be you must get the obd code one more time for the obd may have the wrong code before.