Hi, check for Codes in engine computer. If engine performance is reduced due to computer detecting fault turbo will not work properly. Maybe you have done it all ready, but I just wont to be sure.
Hi, back pressure sensor is treaded on top of a pipe that connects to exhaust, this pipe is plugged with carbon deposits and that is why no pressure there, best way to remove and replace.
Code P0603 is power loss to computer Keep alive memory, but if not coming back, it is just old code.
HERE read this, it is service bulletin from Ford if your injectors have not been serviced lately. this may be the problem.