Well my car has been running like poo for awhile now so I decided to do another tune-up. I read a post about this product called Mopar Combustion Chamber Cleaner. http://www.outreach.psu.edu/users/res122/DSM/ So I use a can of this stuff and then put in a new set of NGK plugs and there is definitely a difference. My engine is running SO much smoother and those horrible misfires at low rpms are gone! So….I recommend that on your next tune-up that you grab a can of this stuff and clean up that carbon build-up.