my car is havin problems. when just driving around it runs fine. however, as soon as i start to get on it, there is a bad hesitation and it starts missing around 3500 rpms. i have changed the plugs, it has new coils and wires, the fuel filter was just changed. it keeps throwing the code p0171 which is bank one lean (this is the only code). i took it to the dealership and had them run it and they suggested a bad maf sensor or possibly fuel pump. they said the injectors were fine. if it were an o2 sensor could it cause these problems(the o2's only have around 1k miles on them). so, what does everyone think it could be and what should the gap on the plugs be. any help is appreciated.