Transmission Valve Body physical failure causing jerking and abruptly reducing speed to 30 MPH. Vehicle is available for inspection Safety of driver and passengers included abrupt deceleration changes risking physical injury to persons and sudden loss of control of vehicular speed/acceleration risking accident/collision with or by other vehicles. Vehicle has been inspected by dealership and is awaiting new part for 100+ days Warning indicator for service check illuminated but then reset and turned off without incident. Issue with driving occurred with second incidence of service check warning, and vehicle was taken in for inspection/service.