2005 Monte Carlo shifting extremely hard on initial takeoff from a complete stop. About every 3-4 weeks car jerks violently forward. Once out of first gear, the car runs smoothly. Took the car to a Chevy dealership who was able to duplicate the issue and confirmed problem with the valve body. Valves, gaskets and selenoid replaced at a whopping $1400. No other major mechanical issues with the vehicle, I'm the original owner and car is maintained in exceptional condition.