I have a 2012 f150 3.5l and I had just replaced the engine with a remanufactured one, it also has brand new turbos and other parts as well. However after putting my new engine in I had a bunch of fuel problems. So long story short I have replaced the fuel rail, injectors and high pressure fuel pump. Everything then seemed to run fine but now I have a problem where my truck wont shift unless I let off the gas. I've looked everywhere and have heard numerous different answers so I am hoping y'all can help me out. Also the only code I have popping up is low fuel rail pressure.