I have an 01 chevy malibu with a 3100 motor and today my check engine light came on and my trans is shifting hard into gear and as it shift while driving around town. I went to the part store and had them read the computer to see why the check engine light was on and they said its reading hot but i have change the temp sensor and all that deals with the cooling the car. I need help on why its shifting hard into gear and while driving and why it made my check engine light come on I need HELP. Can anyone help please