I own a 2000 mercury mystique that has 134,00 miles on it. My check engine light came on and it seems to have a miss or hesitation in the engine while in idle. I Used an actron code reader and it read : P0171 which is system too lean (bank 1) and p1383 which is Variable cam timing over-retarded (bank 1) , what exactly do these codes mean? I am a do-it-yourself repair lady and I have not figured this one out yet, please help.