I’ve had better luck with a couple treatments of the B-12 Chemtool “Total Combustion System Cleaning Kit” then I have with many, many in-tank treatments. I’ve almost decided that the in-tank cleaners can’t really clean combustion chamber deposits with any efficiency. I think they do well on valves and injectors, where the cleaner is in more direct contact with the deposits. It’s hard to imagine how the in-tank cleaners, in the small dosages that are used, can really attack combustion chamber deposits.
Valvoline synpower fuel system cleaner is pretty good. You can also try the maxlife fuel system cleaner, its identical to the synpower and half the price.