The ride was pretty awful. It felt like the chain was a rubber band. Sometimes you'd pedal, and it felt like nothing was happening. This is because the distance from the crank to the rear wheel would change as the suspension compressed - alternatively tightening and loosening the chain as you pedalled.
This is the dilemma; what do you do with a bike that just doesn't ride very good, but is still pretty cool, just for the fact that it even exists, and exists in such great condition?
Lots of vintage builders wrestle with this issue. You finally find that frame you've always wanted, and now you need parts. Buying a parts bike is way easier than buying everything you need piece-by-piece, but what if the parts bike you get is in really good condition? It might be an uncool or unpopular brand, or a poor design like this TREK, but even so, it's hard to break it up when it's so clean.
That's the dilemma facing the TREK 9000 above. A Facebook vintage group I belong to tells me it's in a Salvation Army somewhere in Maryland for $75. If you really wanted to ride this sketchy artifact of early suspension, I think it's a good deal - depending on whether or not the fork still works.
But if you needed parts for an early 90's frame, the black Shimano LX parts here are excellent. And they are getting hard to find for reasonable price these days. $75 is a score.
This will sound blasphemous, but I don't see any reason to put this bike on a pedestal just because it's old and in good shape. It's not fun to ride! Put those parts on something good and cool, and put the frame on the wall.