about four weeks ago my 2003 4.7 2rwd Durango started to miss fire so I changed the spark plugs which did not fix it so I took and had a code reading ran, it come back saying Coil number 2 was miss firing. I went and brought a new coil and replaced it. But after about three days she went back to miss firing. After looking at the coils packs I found out there is a difference between the number the old one is 56028138AD and the new coil pack number 56028138AF. Could the new coil pack be wrong?

 

It should be the same part, I believe the letter at the end indicates a version number change.

Take your original coil and swap it with one from a different cylinder and see if the problem moves there. It could be as simple as a bad wire / loose connection to that coil.

Also pull the plug and look for fouling, cracks, damage to the insulator, etc. If in doubt at all replace the plug, they're cheap.

Bob