Wierd possible suspension problem

Alright i've had this problem with my 95 tahoe ever since i've had it. it has 96,000 miles and is a 5.7 V8. you cannot align it and the it shimmys and shakes really bad when you get past about 65. I do have 18" panther rims that came with the truck. i've replaced the steering gear, gotten it aligned at 3 different places, gotten the tires balanced, gotten new tires, new shocks and i'm finally resorting to the fact that one of my rims could be bent and causing this. but my truck also has a bad problem of what feels like loose suspension. going around curves there is a lot of pitch and roll. it's very sensitive. bumps are also very noticeable. any ideas?