I have a 2009 Chevrolet Impala LT. When I drive in D it won't go past a certain speed but when I drive in 3 it sounds faster than what it's going. It will be at 60mph and the reader will say at 6 when it should be between 2 and 3 on the meter. Then as soon as I do a sharp turn it will jerk and go back to normal, it drives normal and the reader is normal. And it will stay normal for the rest of the time I'm driving until I turn my car off and back on I will have to make a sharp turn for it to stop. What can it be??!!