How can you guys make the determination that the plugs are bad? (other than they look worn/eroded).
My wife's 96 Duratec has about 35K on the Bosch +4s. The engine idles so smoothly, that you can't even tell that its running. Accelerates well too.
I've read a lot of Bosch bashing here, but have had an OK experience w/mine.
I changed the original plugs at 50K. All still looked fairly good, except for the front ones from each bank, which were eroded much worse than the others.
On a similar subject, I believe Hot Rod magazine dyno'd plug wires and found all were pretty much the same too.