I've used it most often as a water dispersant in marine fuel tanks, and as an injector cleaner. I've also used straight acetone into the fuel tank with better results.

To remove the carbon deposits in the engine, spray water into the intake with the engine at high idle. Anyone who has ever seen the cylinder results of a blown headgasket has seen how well a little water works in removing these deposits. A small spray bottle will work - remove the air cleaner and have at it.

I dump a quart of atf into the oil about 100mi before a change, too.

Not responsible for advice not taken...