MrBlak

My 2008 V6 (73k miles) started throwing a CEL about a week ago (P0302). So I changed the spark plugs and spark plug wires, and erased the codes, but after about 100 miles the misfire at Cylinder 2 came back. I checked the coil pack, and port #2 was covered in black dust, and the other 5 were clean. So I cleaned port #2 and erased the codes. Again after about 100 miles the code came back, but this time along with (P0171).

So my questions:
Bad coil on the coil pack? Should I replace it? And doesn't (P0171) have something to do with the MAF sensor? I have everything stock on my car, no mods whatsoever. Any idea on either codes?

Thanks in advance everyone. This is my first Mustang and in the 4 years I've had it, I haven't had a single problem until now.