When I changed out my plugs and wires cyl 6 wire was actually damaged, like PO didnt use dielectric grease on the connection and broke the connector while trying to disconnect it from the plug. Its fine now, or so I thought, havent checked the injectors, ive run cleaner through the system and it netted me noticeable improvement I n my mpg...maybe I have heavy deposits and could use another dose of injector cleaner.