1996 Jeep Laredo front end shudder

Hi, have a 1996 jeep grand cherokee laredo, 6cylinder, auto.I was driving at highway speed and hit a rough patch of road for a few seconds. The front end began to shudder violently, like it was falling off.I pulled over, and found nothing obvious, resarted driving and all was fine again, went a few hundred feet and it happened again, once again found nothing and continued, with no shake after stopping. Drove about another 50 miles on smooth city roads then it returned on the highway. Once you stop, the symptoms disappear. It seems to start after going over a rough section of road, or bump. Was told it may be the steering damper. It was in 2 wheel drive at the time. Would appreciate any help. Thanks.