Don't forget too, that water will get down into the spark plug holes around the boot - especially in numbers 4 and 8. At 100K mi. I replaced my plugs but started getting misfires on 8 so I went back in and found sitting water. Maybe I did not seat the boot correctly. I cleaned it all up, put lots of dialectric grease around the boot and have not had a problem since (2 years). Oh ya - 137k miles now on the original COPS, boots, and springs. Good luck, whatever you find.