i have a misfire so i need to change my plugs and a coil on 4........should i just replace all the coils? also i heard that it could just be the boot on 4 and my coil is fine......also what all do i need....i heard i need some sort of grease that i put on the end of the spring in the boot....so i need to know what plugs i need, coil, and any greases or lubes