Braidyn23

Hi i have a 2004 F150 XLT 5.4 4x4 and have a idle issue with shaking, along with when accelerating and reaching speeds of 65 or more it shakes big time, thought it was something with spark plugs, coil packs, o2 sensors, or injectors but changed and checked them, thinking it could be a issue with the mass airflow sensor or pcv line but not sure, it has the engine light on a gets a code of system to lean. Could there be anything that is a major cause of this? thanks