I'll back Darin up on the Bg 44K recommendation. It is made by BG Products and sold at some NAPAs and some dealership service depts. Really potent and good stuff. On most vehicles you have to readjust the idle after it cleans all the gunk out of the fuel system, no kidding! It is like $20 a can though, ouch. My bro worked as a mechanic for 8 years and his independant shop used all the BG products exclusively, they make a bunch. Me and my bro both hate additives in general btw, there are a a (very) few good ones, BG and lubeguard being chief among them. Pretty much anything you can get at the auto parts store, except chevron techron are crap though.