If you lowered the rear with Progressive 11" then that's your problem !

 

+1 on that. A friend of mine had the wobbles on his touring model and the GM of our dealership told him that front end wobbles almost always are cause by a problem with rear alignment or stability.

 

New to the forum, but here's my 2 cents. My '04 FXDX did the same type of wobble, but maybe not as violent. After pulling my hair for a few weeks, I finally found the upper engine mount/brace bolts loose where they bolt into the cylinder behind the horn mount. Tightened bolts. Problem gone, steady as a rock to at least 100. Hope your problem is this simple.