I've got this same problem. And this was happening before my new OME 913s, wheels and tires.

It's like this. At any speed above say 40mph or so, if I hit bumps, the rear tires don't feel like they track correctly and land out of plane with my direction of travel. It's kind of hairy. Can't tell if this is happening in the front also, because the yaw from the rear is far more pronounced.

The bumps don't need to be huge. At all. Just enough turbulence to left the tires and I'm feeling it. So I can't imagine that the bump stops are coming into play here. Especially after my lift.

My wrench says sway bar. Does this still sound right to those of you in the know here? Also, The Energy Suspension bushings, are those that JoFotoz listed still the optimal choice? And while I have my wallet out for the sway and bushings (if indeed that's the collective response here), are they any other tidbits like new bump stops (suggested model?) I should get BEFORE I go full monty and do the shocks? Remember, OME913s and 285/65 R18s.

I welcome the wisdom.
-V