As above the phase sensor, or more specifically it's wiring, look to see if the wiring is all cracked and broken off, the earlier sensors had shit wire insultion, later ones with red/blue wires were/are ok.
Also have a wiggle of the crank position connector, the connector loses it's grip, and this can cause all amnner of odd problems like this, almost defo lecky in nature.
How old is the fuel pump ?, have you rewired it, needs the fuel pump and fan rewire if you want to keep the engine healthy, as a minimum.
tabetha