nytrdr24
+1y
if the tranny fluid/marvel mystery/seafoam doesn't work, about the only other thing to do is pull the lifters, and soak them in gas, then squeeze them inbetween your fingers and work them, this is best done while still submerged in the gas so it will get all the buildup that is internal to the lifter out.....but if your gonna go to all this trouble you might aswell just put new ones in....
another suggestion, if your gonna use the marvel tranny mystery seafoam fluid, I wouldn't suggest doing it & putting a load on the engine, and I wouldn't run the engine very long after it comes up to temperature.....as ma-chick says, it is a detergent, and will relieve any carbon buildups like a champ....but it is not a lubricant, and if used in too high of a concentration will not properly lubricate your engine, and the extra friction can cause things like piston rings to crack and bearings to seize especially if you are putting a load on the engine, or are running it at its max rpm....
the way i've done it is to put it in the oil, bring the engine up to operating temp, and shut it off & let it cool, and cycle it like this several times, then change the oil out, and only run that oil for a max of 500miles, then change the oil again, this should get rid of any residual mystery fluid you have left in the engine......