ROCK HARVEY
Full Access Member
I have a suggestion that hasn’t been mentioned yet: Liqui Moly Diesel Purge. It’s supposed to clean built up carbon off of the injector tip and chamber. The way you’re supposed to use it is to hook up your fuel intake and return hoses to a container full of diesel purge, and just run your engine off of it until the container runs out. The VW TDI guys swear by it, and you can find a number of videos on YouTube about it. You might try soaking the rings with it as well.