Checking plug gap is much easier ... reason I mentioned this is that plug gap is very sensative to idling well. My Explorer's recommended gap is 0.054 and I had them gapped at 0.057 by accident and it idled like crap and felt like it was missing at constant RPM runs. Gapped them down to 0.052 and she runs and idles SMOOTH! Don't underestimate the power of thousandths of an inch when it comes to plug gap!
