Hello, I hope the following is of assistance.
The most common fault to cause the engine to cut out on this model is a fuel injection pump fault. The fuel pump on this engine is fully electronic, the electronic section of it has circuit faults causing it to lose communication with the engine management or it detects a timing fault that may cause engine damage so sends a message to the engine management requesting engine stop.
The best way to confirm this is to have a diagnostic check of the engine management carried out and retrieve any stored fault codes, the codes for pump failures are usually P1564, P1666, P1563 and P0149. If you want to try to diagnose this on a DIY basis then an example of a code reader is http://www.ebay.co.uk/itm/Super-Diagnose-Tool-Scanner-Vehicle-Sensor-Data-Review-Analysis-EOBD-OBD2-Scan-/150977377016?pt=UK_Diagnostic_Tools_Equipment&hash=item2326f3f2f8 if the pump is at fault then the cheapest option is to have it repaired as a replacement from Ford is around £750 to buy. A good company that I've dealt with is http://www.ecutesting.com/bosch_vp44_diesel_pump_repairs.html
There are obviously other concerns that could cause the engine to stop such as the fuel gauge been incorrect allowing you to run out of fuel, or other sensors or actuators failing other than the pump but start with checking for stored codes.
Let me know if I can help further and I'll reply as soon as I'm able to.