There is some foaming engine cleaner stuff that works pretty well, I can't remember the name.
I got a pair of heads hot tanked. Those tanks are filled with some really nasty stuff and it got off all of the oil and most of the carbon deposits. I think it worked pretty well, but I'm still going to have the chambers and the exhaust ports sand blasted to remove the last of the baked on crap. I think that would work realy well for an intake because nothing is really baked on, just a lot of accumulated grime.
I'm sure a regular solvent tank parts cleaner would work well also.
Good luck