WAY back in the day I heard it was good to clean your pistons with ATF.
I took a water bottle and did a half ATF/ half water mix.
With the engine at about full throttle it squirted the mixture down the carburator of my FJ40 (Chevy 327 sm conversion enigine)
It died a few times as I put in too much "mixture", probably didnt help, probably made it worse.
Im sure its an old wives tale, even though its not exactly the same thing, but same idea