I have a 2003 4.6L with 174500 miles and have been doing a lot of work to her and want to know if I should have replaced the COP's when I did the plugs. No codes very small mis at idle but runs great. Getting about 17 mpg, Already cleaned the MAS and TB. Replaced everything run by the drive belt but the AC and harmonic balancer. Plan on keeping her forever

 

cop's can get expensive.. I know thru dealer their around 130. bucks each.. If its running fine, has power, and idles ok... Dont mess with it..