2003 Ford F-150 Ignition Coils

I recently had to replace one of the ignition coils due to a diagnosis of the 7th cylinder misfire. I bought the part and replaced it myself with little trouble. Two days ago, my 03' F-150, 5.4L began having the same symptoms as before, so I brought it to Auto Zone, hooked it up to the diagnostic machine and read that this time the 5th cylinder had misfired. I bought another coil and replaced it and thought my problems were over. The next day while driving down the highway I began to feel the "spuddering" again so this time I thought it might be the spark plug. I bought and installed a new spark plug for the 5th cylinder but this did nothing to solve the problem. It was back to the diagnostic machine and this time it read "Ignition Coil E Circuit Malfunction". After speaking with a few mechanics, we came to the conclusion that the wire harness that plugs into the top of the ignition coil must be bad. I bought a new harness from the Ford dealership and spliced it in and the truck is still "spuddering" when I hit the accellerator. I am wondering if anyone else has had this problem and/or some guidance on what to tackle next. I apperciate any suggestions.