Please help me... I have a 2000 Mazda Protege with a ZM engine. The transmission is malfunctioning; it shifts into 3rd gear on its own and gets stuck there, making it impossible to go uphill. To get the transmission working normally again, I have to turn off the car, but after driving for a short while, it shifts into 3rd again and can't go uphill. The strange thing is that it's not throwing any error codes. Can anyone help me?