Hello, I hope the following is of assistance.
There are a couple of common concerns that could give the symptoms you describe.
The glow plug lamp on this model acts as an engine management warning lamp, if a fault is detected by the engine management control module (PCM) the lamp flashes and the engine will either lose power or cut out completely, a fault code will also be stored in the PCM.
Fuel pressure concerns can give this symptom, if the fuel pressure is outside preset parameters the PCM detects this and if there is a danger of engine damage then the engine will cut out, when restarted if the pressure concern is no longer there the engine will start and the light remains off until the fault is detected again. As you've already replaced the fuel filter any further investigation relating to fuel pressure needs to be done in the correct order, the fuel pressure needs checking while the injector fuel returned values are measured at the same time, the results of this can help determine if it is a fuel pump or injector concern. The fuel pressure needs to be measured electronically due to the extreme pressures involved (up to 1600 bar) so is not a DIY operation.
Another common concern is a camshaft sensor fault, if the sensor body is black then this will need replacing with a revised grey sensor and a jumper loom to connect to the engine bay wiring.
As I mentioned earlier when the glow plug lamp flashes a fault code will be stored in the PCM, start by having these fault codes retrieved as without these any work is just guess work, the code for a camshaft sensor fault is P0340, fuel pressure concerns tend to leave P1211, P0251 and sometimes P2291 or P2288.
If you want to retrieve the codes on a DIY basis then an example of a scan tool is http://www.ebay .co.uk/itm/Car-Fault-Code-Reader-Engine-Scanner-Diagnostic-Reset-Tool-OBD-2-CAN-BUS-EOBD-UK/221239134310?_trksid=p2045573.m2102&_trkparms=aid%3D555012%26algo%3DPW.MBE%26ao%3D1%26asc%3D19100%26meid%3D3252127257315112297%26pid%3D100034%26prg%3D8668%26rk%3D1%26rkt%3D4%26sd%3D221252642417%26 which would save you money rather than paying a garage to retrieve the codes.
I hope this helps but if you have more questions regarding this let me know and I'll reply as soon as I'm able to.