I had a 396 Chevelle that was running like crap. I was young and didn't know much about cars or mechanics then. My uncle had made a career out of it though. He came over and told me to fill a small Coke bottle with water. He said to get in the car and keep it revved up. He slowly poured that bottle of water down the carb. while I kept it running. The car smoothed out and purred like a kitten. We pulled a plug and it was clean as a whistle. The water got into the cylinder and was super heated is my understanding now almost like steam cleaning the internals. It knocked all the carbon deposits off the valves, plugs, etc...just have to be careful not to hydrolock the engine. It was an old mechanics trick that I'm sure he had used many times over the years.
Seafoam probably does something similar, but in a safer manner being added to a tank of fuel.
Or cleans whatever injection setup you have - injectors, carb. throttle body,
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