While driving during morning rush hour traffic approximately 0645, the vehicle became sluggish and eventually began shake vigorously. i was in the passing lane with vehicles driving at at speeds up to approximately 65 to 80 mph. the drive train error came on and indicated 'drive moderately.' given that i was 3 miles from entering the monitor merrimack memorial bridge tunnel i had to make the decision to stop in the past lane or coast to the center lane between and on ramp and two lanes of traffic whizzing past. the vehicle would not go any further so i placed it in neutral to get to the safest possible scenario (between the traffic an on ramp).