Need your help as I am new to this. A couple of weeks ago my service engine soon light came on. Went to Auto Zone and of course the scanner indicated an 02 sensor problem which I now understand does not mean to change the sensors. I did. I rechecked with a scanner and not only did I get the P0155 code but I got the P1151 code. I have since changed the electronic vacum regulator and the fuel filter (under driver seat). Today after turning the engine light off it came back on and now I have a new code of P1400 and my engine studders while I am driving at a constant speed. Help.