My Vehicle has no warning signs lights that it has an problem/issue to warn. When driving to 30mpg the vehicle does a forceful jerk forward to a stop causing whiplash effect to driver and passengers. When vehicle comes to a near stop to traffic or light it creates the same effect. This is a constant through the entire driving trip. I have taken it to several mechanics and they have accurate or certain solution. In the attempt to find isssue transmission service, oil change, and spark plugs have been changed. Brakes have been check as well from professional service mechanics