Buy new ones! I had misfiring at around 70k miles and it was the because of the boot. Just because they look like new doesn't mean they're not going to fail. Mine looked great, but, there was a tiny arc trail that went up the plug, under the boot to the high voltage side. The boot was suppose to prevent that!
Last edited by scottjoh; 08-18-2012 at 06:19 PM.