Over time it became more & more difficult to start the vehicle, until it finally would not start anymore.
All the ignition components are new, so are fuel filter and pump.
The engine starts immediatelly when a small amount of fuel is poured into the throttle body and remains running after that until it is shut off again.
Could the ignition lock be at fault here?

 

Sounds like the pump or possibly the fpr. What brand of fuel pump did you put in ?