The problem was found and fixed, and the sound I was hearing wasn’t entirely electrical in nature.
Apparently when my spark plugs were installed at the factory, the person in charge of putting the plugs into the engines cross threaded the spark plug in question. It was actually the 5th spark plug in a V6 engine, which would have put it on the side of the engine I was hearing noise from.
So, when I pulled out my spark plugs the other day, I didn’t think any differently when they all were a bit difficult to remove (which, I just wrote off as a result of rust, wear, etc.). When I put them all back in, which was as smooth as butter might I add, I didn’t even once contemplate checking the threads.
The clicking noise I heard was a combination of compressed air and an electric spark that were escaping the engine through a small gap because reinstalling the plug did not put it where it needed to be.
My mechanic was able to re-tap the hole and save me the misfortune of re-machining the heads or outright replacing them. He gave me grave news, however, in that there is no guarantee that once I replace them 90,000 miles down the road that they will go back in or even hold.
Naturally, this has introduced a new dilemma into my life: who should I be going after to correct all of this. CarMax (who I bought the car from) certifies their cars via their checklist (and this area of the engine is covered under that) and their manager told me that if they could determine my claim to be factual, they would take steps in correcting my issue because of their gaurantee- what that means I don’t even know at this point. Aside from a stripped Motorcraft, factory spark plug I don’t know how I’m going to prove this. My bigger fear is that they’ll remove the plug, say they found nothing wrong, and not be able to re-install it - which could mean I’m SOL.
I hate to keep asking questions, but what would you guys do? Pursue CarMax and press that they certified a portion of the car which wasn’t up to snuff? Cut my losses and just deal with it 90,000 miles down the road?
Again, thank you everyone.