jamie930

When you changed the plugs did you change the COP boots and springs?

I had misfires come back after changing the plugs. Change the COP boot and spring misfires went away

loganz71

Nope just the plugs

jamie930

Rock Auto has a set of 8 for around $30 shipped to you via USPS

STANDARD MOTOR PRODUCTS Part # CPBK240

when I changed them out the springs were about a 1/4" longer than the stock ones, but I don't know if the old springs were shorter or had been compressed.
The OEM springs did not come out of the boot , but the news ones came out the boots about 1/4"

Mod (Ret.)

Unless you are wanting to do some costly preventative maintenance, I'd only change the COP boots and springs as mentioned by jamie930, and leave the plugs you have already replaced 30K ago alone. If the COP's themselves are not throwing a code, then they are still good.