Hey. It turns out i just wasn't using the regulator properly. I wasn't opening it up more after the original lighting of the flame and adjusting the air intake. I have been getting great boils now. Sometimes i get propane freeze near the end of the tank, which greatly reduces the flame intensity. It sounds like you know what your doing, so this probably isn't much help. It could be that it just too cold and those keggles probably aren't the best insulators. May want to try insulating the keggle before modding the burner.
If you have a lid (wifes skillet cover), you can (briefly) cover the keggle during the boil and the roll will come back.
For what its worth, the beer from the original post turned out to be fine without ever rolling.