I don’t think sucking it (sea-foam) into a running engine will do ANYTHING except blow 98% of it out the exhaust and make a lot of smoke…
Rotate the engine to TDC, then 90 degrees more, to position all the pistons at mid-point in their bores…Remove the plugs and introduce 3 or 4 ounces of Sea-Foam or Rislone into each cylinder. Let that soak overnight. Turn the engine over by hand to clear the cylinders, then spin it with the starter, install the plugs, and fire it up…After one drive cycle, I would change the oil…