I had one that shake after a bump in the road. Did about three turn stop to turn stop figure eights in the backyard and that cured about 90% of it. There was some air hiding in the system somewhere.

 

Alignment spec is 0 - 2 mm toe out (front of tires vs rear of tires at axle height). Agree that attention to tires is important, spec pressure is 26 psi for 235/70 R16 front tires, rear 34 psi. Make sure the lash in the steering box is adjusted near zero, but not over tight. If still bad after new bushings for the radius arms, then maybe try rubber bushings for the panhard rod (vs poly). Maybe tighten swivel and wheel bearing preloads a smidge, and make sure the stub axles are not worn out.

My steering would wobble driving over train track crossings (30 - 40 mph). Fixed it with new panhard and radius arm bushings, swivel and wheel preload adjustments, and careful steering box adjustment.

 

Yes, replaced..sorry I forgot to list that.