02 f-150 w/4.6 and 60k on it started missing and gave me a PO307 code so I visually checked the the #7 spark plug and boot which looked fine.
My question is can I just replace the spark plug and boot to try and cure the problem and can I buy just 1 boot from the dealer?
These spark plug wires and boots look like nothing I have seen before the look like thick speaker wire. Thanks, Ryan

 

That funny looking boot is actually your coil for that plug. You have a coil on plug ignition system (wish I had that!). Try replacing your plugs first, then move to the coils packs. It is not uncomon to have a bad coil pack, however it is not the first thing to replace.