2006 Dodge Ram death wobble

I have a 2006 dodge ram 3500 with a 6" skyjacker suspension life, since I owned the truck at 60000km there has been periods of time when I experience the "death wobble" then it will go away for several months then come back and go away again. I had all the worn out suspension parts replaced and it didnt really seem to make a difference. I reasently put 7000km on my truck in a week and the last 200 km I had about 15 really bad wobbles when my speed reaches over 100km/h, why would this happen and is there anyway that I can get rid of this?