Ad one more.
If the Valve/s in the Fuel Supply Lift Pump are not sealing the Fuel will drain back to the Fuel tank and the Lift Pump sort of loses prime.

Does the problem go away or improve if the Fuel Tank is full or if the rear of the Car is higher than the front of the Car when it sits overnight?

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84 300D, 82 Volvo 244Gl Diesel