I agree with Phil and jacktuttle... Something is wrong, or it could be a combination of a few little things. Once lifted, all the settings/conditions are just a little more critical. There is essentially less margin for error.
IE, your toe-in is 1/8" too far in, and you have one bolt on your upper control arm 2 revolutions too loose. Strange SLIGHT combinations like this can compound the forces and throw the axle into a DW.
But 9 times out of 10, ok maybe 8 out of 10, it is related to the track bar. I would retork, check for sloppy TRE's/balls, balance wheels, dial in your toe, caster...
Like mentioned above, caster is one of those things that compounds other variables easily. If your axle is too upright, it can make another slight problem bigger. You really are going to need to go through each individual spec, torque, alignment, setting, etc and make sure they are right on the money.
Another thing that further "dials in" your rig is the steering. If you are lifted, you already have steeper angles for you TB and DL... This in itself can be "one strike" against you that can be a mulitplier to another slight problem. Basically, dont necessarily look for ONE thing to be wrong, but make sure EVERY thing is perfect.