It COULD have been 90K. We got the car at 60k, so *perhaps* the dealer changed them but used copper, but my bet was they were the factory plugs just left in. I replaced them with Motorcraft platinums, though.
That said, the plugs were gapped over .080 easily when I took them out, and they were pretty rounded. The car started skipping on the highway one day, but wouldn't do it around town, and my guess was it only did it once the plugs got hot from high RPM. I wanted her to change them earlier as I "felt" them ever so slightly being bad and having some harder starts. I changed the coils to random yellow Chinese ones from ebay that were $35 a set, no way we could afford Motorcraft coils for that car ($80 x 6) but the Chinese coils seem good and it's been over 10K.
That they fired that way is probably a testament to how powerful and good Ford ignition and coils are, not the plugs themselves. There's a reason track cars run EDIS ignitions even on imports. If you have a powerful enough coil almost any plug will fire. On the same token but unrelated, on my old Sentra I found out the spark color mattered a lot. I had an older coil in it and it really lacked power even with new plugs, and the old coil wouldn't even allow the car to start with rounded .080+ Bosch conventionals my father put in, it started right up with new NGK coppers, though. But once I put in another $12 Chinese ignition coil the whole car seemingly came to life.
