I have not heard to many stories about the autos, other than they are quite weaker than their predecessor 4 speed unit. Usually when a tranny slips, the engine does not hesitate, the Engine RPM's raise up high, (4-6K RPM), but the car does not go forward. Similar to slipping clutch in a manual. If this is what your car is doing, then yes, you could be slipping, but if the engine is hesitating, stumbling, etc, then you some other issue, like a coil pack, lean condition, bad gas, etc..