I have this 98 3.1 Lumina, with this kinda "wobbling" sound, more like the sound coming from a washing machine in the spin cycle without any clothes in it, but a lot more muffled. I've changed both my drums and shoes, thinking they might be the problem, but it's still there, comes and goes when I go up or down inclines, braking and just straight driving. I'm not sure if it's the wheel bearing, out of balance tire, probably worn struts, or something else entirely. Any ideas?