Sea Foam or Deep Creep both do amazing jobs are restoring lost power. Been around for ages, and both cheap and available at all auto parts stores. The results can be far more dramatic than anything you'd ever observe from standard FI cleaners.
WOT quite often significantly slows the process, in like a teardown on some engines run hard for 70-80k will have barely any carbon. Hell, if you want just inect water in your intake, that'll take it out.