New parts doesn't mean that the parts themselves can be eliminated as a possible problem. This can be especially true with electrical parts when non Original equipment parts are used. It's also possible that a electrical connector isn't fully seated, or a vacuum line was accidentally left off.Or maybe the wrong spark plug was used. Experience has taught me the hard way to use only OE parts, rock auto is a good source to determine whom is the OE manufacturer. I would encourage you to investigate these possibilities before doing anything else.
^^^^ agree 100% with Bob. No name aftermarket electrical parts are often JUNK. For coil pack, use ONLY the OEM Motorcraft part or the BWD (Borg Warner) part. BWD is big OEM supplier of electrical / ignition parts to Ford. BWD coil pack is a little cheaper than the Motorcraft, but still not cheap. You get what you pay for.
What was the exact code????
Check plug wires to be sure none are laying on hot engine parts or have damaged insulation. Motorcraft plug wires are the way to go and available from RA for a decent price. Might want to pull plugs and look for correct gap, and carefully inspect the insulators for even tiny cracks. Any cracks at all = plug is junk. Be sure someone didnt put Bosch plugs in the engine. Bosch plugs do not work well in Fords from my experience.
Eye inspection is VERY important. Old school you could ohm a wire and tell if it was OK. Not any more. As in the pic, there is a reason I pulled one year old plugs and OE wires for scrap.
Careful visual is key. And I have had the cracked coil this also. MC plugs and new wires and now 7 years later it runs perfect at 193K. And in the pic, there is a brand name, and the top electrode is very loose in the MC wire end.In fact that plug is loose on any old wire end I have in my parts box. Just plain made wrong.