Seafoam. It is fantastic stuff. I just did both my cars (87 765Ti and 84 244dl)... a very, very, noticeable difference in both vehicles. The wagon especially accelerates much better at low rpm's, both seem to idle smoother.

It took all of about 10 minutes per car, then a few miles of driving to blow all the smoke out.
About a cup of distilled water first, then a full can of Seafoam each. I used the manifold port where the small vaccum line from the flame-trap "Y" is normally connected.

http://www.seafoamsales.com/motorTuneUpTechGas.htm