Changed the COP's on the front of the Escape 8 years ago when plug 4 had issue's. Didn't want to pull the intake so left the back ones. Randomly would get a code over the last 2 years on 2 and 3. Finally got bad enough had to do it, I've had the COP's all this time lol. Any repair is easy after R&R the head on the Focus. After I changed those that the wife complained it wouldn't get out of it's own way. There was a rock hard piece of carbon in the back cat, blew out the gasket a the flex pipe first. Oops that laziness got me. Had to warn her not to put her foot in it, it'll light them up if not careful.
If you reside in a strict emission state I sure wouldn't those misfires go on very long.. $$$$$
If you reside in a strict emission state I sure wouldn't those misfires go on very long.. $$$$$