Well, if you decide on one of the PEA cleaners, follow the instructions on the bottle...get your tank as empty as possible, add the fuel system treatment, then fill up the tank (this is so that the cleaner can mix evenly in the fuel.) Try to do this just before a long road trip, because a hot engine is a much more favorable environment for cleaning...a few hours on the road with a PEA cleaner will do wonders for a dirty engine. Then, try not to fill up until you are near empty again, to give the PEA the proper concentration in the fuel to clean the best.
If you want to get adventurous, an overnight piston soak with Marvel Mystery Oil might be in order. Pull your sparkplugs, pour in some MMO down each hole, and leave it overnight. The solvents in the MMO will clean up the piston tops and the top compression ring pretty well. The next morning, siphon as much of the MMO out as possible, put the sparkplugs back in, and turn the engine on. It may smoke for a bit as it burns off the excess oil. Take a drive around town to heat up the engine so it can burn off the now loosened carbon deposits.