Sea Foam.
No wire brushes, don't even have to take the heads off. You bring it through the carbs (or into the intake through vaccuum). You let it sit a while. Fire it up and watch the clouds of nasty smelling smoke that come out your tail pipe. Just did it on an old truck and practically smoked out my neighborhood.
Follow the instructions and change your oil after using. You can also run it in your crank case oil before changing oil to dislodge sludge, etc. If you've had a big carbon buildup you will notice the difference.