Unfortunately, gas does not dissolve carbon that is the byproduct of combustion. I had a piece of carbon come loose in Moab last year and you would have sworn the engine was coming apart until it passed out the exhaust valve. I’ve seen inside several under 30K mile Isuzu engines (I have 2 VX intakes in my garage) and the black coating that builds up is thick and hard and should be removed - it will not go away with over the counter products although they can help minimize it.