Your truck has coil packs. Easily bought at any parts store. Use a code scanner (if you have a CEL) to determine which cylinder is misfiring. I think its a 10mm bolt that holds them down, unplug the electrical connection and pull it free from the plug. Dont forget to add dielectric grease with the new coil pack.
My 2000 4.6L gave me troubles with these things all the time.
2011 FX4 Luxury SCREW EcoBoost 157" WB Charter member of both the 55 MPH and 5 MPH SHUDDER club