C-Max 1.0 Ecoboost Issue

I've had this C-max and the car had overheating issues and then got a new head, gaskets, rings and most of it changed after all of this the engine starts. It idles really rough and wouldn't rev past 1800 rpm and i checked the fuel pressure in the rail it was really really low compared to another ecoboost from a 2015 focus. I took parts from the focus and put them on the c max and it still does the same , coils , plugs, fuel pressure sensor and also the crank position sensor all have been changed. and the focus runs fine with the c max parts.
I just want to know if anyone has a clue what could be wrong.
Thanks.