350z 5 speed auto car has no acceleration power also manual mode does not work it shifts by itself l. car has codes p1815 p1754 and p1764. it all started when i replaced the alternator but it was throwing out to much voltage due to a faulty regulator AT light came on and gave me those codes after new alternator was installed. car has no power when i floor it and manual mode does not work if i shift down it will give a small acceleration. feels as if car starts in a high gear or is in some limp mode