Ford Fiesta 1.4 tdci?

Hi. I have just bought a fiesta with knackered engine.
I bought a running engine from a breakers, and I saw it running and drove it to test it.
I changed engine over with new filters and oil, and coolant etc ...
Engine starts straight away. but when it gets to temperature it cuts out.
It starts straight after cutting out but runs for a minute.
If you rev over 4000 rpm, it cuts out.
I have changed
coolant temp sensor, another fuel filter, fuel feed pipes and bubble, dropped tank and cleaned out sender unit etc...
I am now stuck, can any diesel gurus help please...Simon