suckky suckky! sounds like you could have an air leak? There is a large rubber gasket/sandwhich plate between the intake manifold and injection unit, they tend to break up! You can get hold of new ones for about £18 iirc, you can undo the four allen bolts and re-seal/check it.
Other problems such as a failing coil/very week spark will cause that sort of thing.
err.. let me think..
Crank position sensor somtimes does it but usually gives bad running/difficult to start, same with the RPM sensor.
Throttle position sensor.. you can strip and clean that, but i doubt thats it, if it does idle.
The last thing would be fuel pressure, change the filter for a start, i guess the fuel pump relay failing might do it too? and of course a faulty pump
Theres some common causes to give you some ideas anyway .
