Oh yeah, another thing that works well: Sea Foam
. Wal-mart has it for $8.97 and auto parts for ~$10.
I found the easiest one to use is the vacuum line to the check valve on the brake booster. Pull off the hose from the valve and I used one of those syringe deals and S-L-O-W-L-Y pour some of it (up to 1/3 of the can) while the engine is RUNNING; you have to find the balance so it doesn't stall. Afterawrd, shut off, let it sit for 5 minutes or so and start-up. Depending on how much gunk you have, may be difficult to start at first and you'll get a crapload of smoke at first, but drive it hard for a bit to get it all burned up. I repeated a couple times over a few days.
Essentially, it cleans out the carbon build-up in the combustion chamber when used thru the intake...One thing I notice though, is it can contaminate your oil a little, so I'd do it close to oil change time. You can also add it in the fuel or in the oil itself, although I like it the intake way.
Dodge makes a similar product (they used to talk about it alot on the jeep boards), but it's a different procedure; iirc, you removed the plug(s).
fwiw, water can do the same thing, but is a different procedure and you have to really have the engine revving. The water mist turns into steam and does a similar thing as sea-foam. That is one nice thing about a water injection system on a forced induction engine
Either way, getting rid of the carbon helps keep detonation at bay (when an engine has a bunch of carbon, it can burn/remain hot enough to spark cylinder mix at wrong time), for one thing, but you can imagine from an airflow pov (valves), it should help too.