Aye Seafoam. You can buy it at Napa for sure. I don't know who else carries it, but I know that the Auto Zone and Pep Boys chains in the Dallas area don't carry it.

The stuff comes in a 16oz. can and is blueish green in color. All of the Seafoam products carry the Auto Marine label on them. Here is a pic of the can you will need to look for:



Note: The image is borrowed from a Tripod webpage, so it may not work.

They also make a product called "Deep Creep" which is the same as the above item, only it is in a spray can. I didn't see these for sale here and just used a spray bottle to get it into my throttle body.