One problem related to vehicle shudder has been reported for the 1999 Ford F-150. The most recently reported issues are listed below.
Vehicle pulls a 5500lbs trailer: whenever slowing down to make a turn on an incline, shifting from second to first gear, vehicle will shutter and jerk violently. Also, rear end virbrates when taking off from a stop. If traveling 70mph and above, entire vehicle shakes. Contacted the dealer, and they can't fix it.