Final update:

Replacing the dislodged vacuum line (the one that goes to the MAP sensor) got rid of the P0105 code (no more codes remained), but the stall/no-start problem was still occurring.

During the latest stall/no-start episode, while one person was trying to crank the engine, a second person began tapping the fuel pump gently with a stick from the rear of the car, and this enabled the car to start. So the fuel pump was replaced and now the car is running fine with no problems for almost a week, so the major problem was probably the fuel pump (fuel filter was replaced earlier as stated above). Thanks to all who provided advice.