P0304 code - cylinder 4 misfire?

What is your question?

I switched coil pack and that did not correct it I also put a new spark plug in it, even though I put 4 new ones in back in May, and that did not correct the problem. Can some one give me some help on what might be causing this code? The engine is skipping a small amount(not bad) at idle. Thanks very much in advance.