I've used Seafoam a few times on different vehicles. It will smoke really bad for a while, but it did seem to clean the plenum out some.
For fuel systems, instead of Seafoam, I like to use Ford's carb. cleaner that pours in the tank. It won't clean the intake and vacuum system, but works wonders in the fuel system and cylinders. The stuffs pretty potent, so mix it with a full tank, and make sure you don't get any on you, or your clothes. Iirc, it comes in a red and white can, and should run $8 to $12. This is what I'd use on a turbo car, takes longer to work, but don't have to worry about pushing any carbon particles through the turbo.