Whats your castor set at .On my Rubicon it would get death wobble until I rotated the axle back with adjustable upper arms.now of course the Toyota doesn't have that , but there are ways to increase the castor other then just the offset bushings. castor plates and or the offset trunion bearings.Not saying its what causing it but I would thing you would want to check its setting. good luck I hatted the jeep when it started doing it .It also had a 4" lift.