violent front end bounce

[DetroitDan]

I just read a thread about this, cant locate it again. I just put my 82 on the road, find that occasionally when i hit a bump just right, the front suspension begins bouncing violently, almost like an oscillating I guess? It's so bad it scares the crap out of me, have to stop to make it go away, but then you can drive again. I have been told numerous things it could be. People say the steering stabilizer, well I ordered a new one, but in the meantime I looked at the old one to see if it was leaking or damaged, it looks brand new! Probably the p.o. had it replaced in an attempt to correct the problem. Others say lower balljoints, I've checked them twice and they feel fine. My cousin told me his 3/4 did the exact same thing and it ended up being wheel bearings. So I checked and the right side had a little bit of play, so I just replaced them. Didn't change a thing. I thought maybe shocks, but doesn't it seem like if the shocks were bad it would just bounce slowly and soupy? This is a fast, ultra violent bouncing, I'm certain a front tire is leaving the ground. It's happening at about 30-40 mph, I wouldn't want to experience it any faster. I feel a little faint beginnings of it at lower speeds, but it doesn't get really bouncing. Overall the truck rides like crap. I understand it's a big heavy old 1 ton, but I am very accustomed to old live axle trucks, and 1 tons. This thing really rides bad.
What about springs, there's none broken that I can see, but if the shocks were bad or something, idk, could they do this? Also, I noticed there are two bumpstops, one over the axle and another behind it over the spring. There are rub marks from contact, and they only clear the spring by an inch or two. I think this is involved somehow, maybe when the truck bottoms out a gainst the bumpstops it is doing something weird.
SO, lastly, I have a set of good front 4 inch lift springs and Rancho shocks, which I wanted to wait until spring to install. No way do I want to try replacing shocks when I already have a good set waiting for the lift. What are the odds the problem will go away when I change the springs and shocks?

Thanks for reading the long post, and hope somebody can help.