So over the last week or so the expy was just misfiring like crazy, not always throwing the flashing check engine light, but it was seriously annoying. So I decided to bite the bullet and ordered a set of the NGK Rutheniums.
The Motorcrafts had right around 15k miles. The gap on all of them were around .034”. Cylinder 1 plug looks particularly bad, which makes sense with the previous codes showing misfires on that cylinder.
The NGKs all measured .028” out of the box, which was what I wanted. Got them thrown in yesterday, and so far so good. Running so much better at both idle and under acceleration. I’ll try to report back over the next few weeks about performance.
Do not buy Motorcraft plugs.