i have a 94 caprice w/4.7ltr v8...
this is the problem...my brakes were squealing so my husband put on front brakes, then the front brakes started freezing while i was driving, we changed the calipers & the brake hoses on the front brakes (both sides)...NOW every now and then my front end (feels like the tires or something, but tires are new and balanced and aligned) starts shaking at around 57 mph....not everytime and NOT when i brake!

could it be something wrong w/the ABS?

i had the same thing happen to my old car, it turned out to be the master cylinder

Probably not your brakes if it shakes will driving and not braking. I'd guess worn idler arms since they are known for failing on these cars.