2006 grand prix GXP with about 230000km, bought the car used about 1 year ago. Accelerated from green light to about 60km/h when the rpms shot up and the car stopped accelerating. Giving it gas would not do anything except raise the rpms. Eventually car rolled to a stop, now it wont shift into drive or reverse, but neutral works fine. Tranny fluid is still red, and at a good level. Gonna change the fluid and filter, but wondering if anyone had any hints at anything else?