2001 olds 4.0l codes p0101,p0121,p0171,p0174,p0300

P0101 Mass or Volume Air Flow Circuit Range/Performance P0121 Throttle/Pedal Position Sensor/Switch A Circuit Range/Performance Problem P0171 System too Lean (Bank 1) P0174 System too Lean (Bank 2) P0300 Random/Multiple Cylinder Misfire Detected More than likely these are all related to a failed MAF Sensor and when you have it removed(since it is connected to the throttle body) clean the inside of the throttle body around the butterfly. This should take care of your problems. The codes will need to be reset after the repairs are made to get the check engine light to go out.