[tubman]

To answer the O/P's question, a lot of folks I know (including myself) use Seafoam for this purpose. Just be prepared to really smoke up the area if you do it right. "drolston" has the technique about right, except the on last dose, we poured in enough to stall the engine out. Then let it sit for 10 minutes or so and restart it. That's when you get the billowing clouds of smoke. I don't know if kerosene works as well as Seafoam, as I have never used it. It certainly would be cheaper, though.