seafoam deep creep is a product you can use to lubricate, penetrate and clean. it can be used in the oil, in the gas or sprayed or poured into the plenum chamber of the engine to clean the carbon build up out, and supposedly help clean sticking valves or help prevent the sticking valves.
The product is also availible in different forms, i think it comes in a liquid that you have to pour in with a funnel and in a spray can WD-40 style with the little red soray straw.
There is a bit of debate as to how much it helps or what it exactly cleans, and whether or not it is O2 sensor safe or not. But i gave it a try and figured the $6.95 price tag for the can was worth a try.
I used the spray can version in my 96 Disco, and i have to say a lot of carbon smoke came out of the exhaust after i used it, and the idle dropped some and is more level then it used to be.
you can buy it at some autopart stores or order it online like i did from here:
http://www.midwayautosupply.com/detailedproductdescription.asp?8740
you can read about it on the manufactureres web site here:
http://www.seafoamsales.com/deepCreepConsumer.htm
if you can wait until the Dweb archives are back up you will be able to search foro and find a plethora of threads regarding deep creep.
hope this helps.