The discs on these are apparently prone to warping. When we bought our 1996 and drove it in the mountains for the first time, I could get a frightening shudder after a few braking episodes - apparently, the discs would heat up and warp, causing dramatic shudders. New front discs and pads helped, though I think I may eventually need to do the same on the back.

But this shuddering pretty well stopped when my foot came off the brake, so that may not be it. I would suspect a suspension problem.