OT: Help diagnose my 96 Jeep Cherokee Classic, Temporarily shakes at high speeds Options

[BigDBass]

When traveling at 50+ MPH, sometimes my trusty '96 Cherokee Classic starts shaking rather violently with some trigger I cannot exactly pinpoint. The whole vehicle shakes as does the steering wheel. I have to hold on to the steering wheel pretty strongly to maintain control. After 5 - 10 seconds, it goes away.

The last time it happened, I was doing about 60 and had to slow suddenly for traffic congestion. It seemed that hitting the brakes medium to hard set it off. The shake continues after getting off the brakes. After a hundred yards or so, it "calmed down".

It also happened when I hit a bump at 50+ MPH, but it's possible I was braking when as well.

I took it to a nearby mechanic (Firestone shop) who looked at it. They said the suspension and steering looked fine, and the tires were ok and wearing evenly. They think the shaking is caused by warping front rotors. But that doesn't explain to me why it keeps shaking even when I'm off the brakes? Or does their explanation make sense?

We're getting a Honda Odyssey Minivan (hers) and getting rid of either my '96 Cherokee Classic (76k miles) or my wife's '98 Cherokee Sport(58k miles). I'd prefer to keep mine rather than take over hers, but I need to figure out what mine needs first.

Thanks!