97 Rodeo rear wheel wobble, losing the battle

[motocip]

I have a rear wheel wobble that I cannot figure out. I replaced all 4 tires and installed new rear shocks. Still have wobble that fades in and out but never goes away. As I drive I adjust the drivers rear view mirror so I can see the rear wheel as I drive and can see it bouncing as if the shock was bad, noticably on a bumpy road, fades in and out on a smooth road. I had the tire shop recheck the tire balance and no change. If the tire is good, balanced, rim straight, and new shock, then what else could be causing this. I was told that a four wheel alignment may be the answer but that does not make sense to me. I have yet to examine the rear axle mounting bushings, but it was suggested. I just find it hard to believe that they could be the cause. Any suggestions would be greatly appreciated. I cannot afford to keep experimenting.

[amigo-2k]

Over inflated tire?

weak busted spring?

[StateTrooper]

Have tire balance checked somewhere else.

Check for seperated tread.

[2eyefishclaw]

bent axle shaft?

[Jungleman]

I think you should check your back bearings