it might be the fuel pump i had a problem where my car would idle ant lights and shake and wasn't good i took it in and the fuel pump was bad and the fuel injectors were bad. OK try this go to any car store or a gas station and pick up some fuel injector cleaner and poor it into the gas tank and by the time the tank is empty their might be a difference. just try that first because its alot cheaper for you to do it than a mechanic.good luck