One little bolt holds that coil pack in place. Once you know which plug/pack it is, they are very easy to replace. If you have a doubt try the front one on the right side (5.4L). You will need a air compressor. You must blow out the hole where the plug sits to make sure no dirt or rocks fall into the engine.
Had this happen on my van. Code indicated #7 wasn't firing. Thought it might be a bad connection so I cleaned and re-connected the coil. Ran fine for a week, then came back. This time I swapped #7 and #5 to see if the problem moved to #5. That was almost a year ago and the miss never returned.
The link above is a great deal and I run them on my truck.
It was recommended to me to get the set for the V10 so you have 2 extras when you buy them.
I'm glad I did because 1 was bad out of the 8 I put on. Instead of messing with sending one back I just put one of the extras on and now I still have one extra good one for another time.
I agree, the Accels are painfully bad, the MSDs are ok, but remember, they can't be better if they are cheaper. In coils, you get what you pay for. I would pass on the eBay ones, and replace the one(s) that have failed with OE Motorcraft coils.
When you check your codes at the local big box parts store (or on your own scanner) the last number of the misfire code will be the cylinder. The back two are a PITA as mentioned, but the others are remove the one 8-10mm bolt (can't recall) unplug the electrical hook up, pull it off and put a new one on.