2003 for expedition 5.4 L no accelaration when driving

have a 2003 for expedition 5.4 L. I have been having problems with this that no one can figure out for some reason. I have no accelaration when driving. It just revs up. I took it to a local machanic and a fordalership. They said change the egr valve so i did that and the dpfe sensor. It still runs bad. I have two codes p0171 p0125 I have checked for vaccum leak. I changed my o2 sensor and mas air flow sensor.. now my check engine light is on and I drive it and the engine keeps running but all power falls off.