If there's a steering damper fitted, it might be brokened .. replacement or removal is the only option.
However, removal means the rest of the steering system needs to be spot on. I've run my 90 without for a while but added a damper when I also added HD steering rods and other stuff that can adversely affect steering.
So, also check, as said above, the panhard rod bushes, they usually feel good when trying to move with a hand, but use a crowbar or long pry bar to lever them. Almost any movement they need replaceing. Similarly the front suspension bushes, trackrod ends, radius arms and all joints. At the rear I'd also check the suspension and trailing arm bushes, as well as the A-frame bushes.
'course, your steering box might also be a tad loose, or something wrong with tyre pressures/sizes/worn treads, there's a host of things that might influence steering wobble so it's worth checking 'everything' .. though I'd do them one at a time, fix it, then start again with a decent test drive and carry on till it goes completely.
