Whether the problem has been suspected as fuel pump, leaking injector, leaking head gasket... this process has worked for me and has minimized the start/stall or start/stumble problems:
- Turn the key on, wait until the chime stops sounding.
- Floor the gas pedal as if to start a flooded engine.
- Turn the key to the Start position and hold it there until the oil pressure light is no longer lit.
- Let the gas pedal up while still holding the key in the Start position the engine should start without stalling or stumbling.