I know I am contrary to popular belief here, but I don't buy that the poly trailing arm bushings cause any problems. I think that is some theory that got hatched by H-T, and just keeps getting repeated. regardless, you had the issue before the bushing so that isn't the problem. I am wondeing if it might be a problem with one of the shocks. Does it feel funny when you turn one direction and not the other? Is it worse over bumpy roads? I think I would still take it to shop, its going to be hard to solve just over the forums, its obviously not something easy.