Allan: Try the fuel pressure regulator. It is a small device right below the fuel rail at about the second cylinder from the passenger side/front of the engine. It has a vacuum elbow connected to it. Maybe that vacuum elbow is broken of leaking, which could cause the loss of prime in the fuel system overnight. Also, check the thermo-switch near the thermostat housing (hard to see). If that switch is malfunctioning, it will negate the appropriate signal to the ECU which could cause hard-starting when the car is cold. The ECU needs this signal to enrichen the mixture on cold startups. Good luck!

Bou Bou