Have you changed the spark plugs in your pickup yet Bob?
I had one of them in the shop because of a missfire. It wasn't a 2008, but it had the 5.4 triton V8. Coil per plug system. Oh man, the two plugs farthest back towards the firewall.
Problem turned out being the owner had changed 6 of the 8 plugs (leaving the hardest two). On top of that they used champion standard cheapo replacements. So they drove it with 6 new champions and two old motorcraft.
Plug and Plug boot replacement solved the missfire problem.