Some of this may have already been mentioned.
Do one at a time.
Disconnect the Vacuum Line from the Vacuum Shutoff. By doing that you are checking to see if the Vacuum Shutoff Valve on the Steering Colum Lock is function OK.

Remove the Oil Fill Cap and see it that makes a difference. If that helps it is likely your crankcase pressure is not venting out of the breather tubing.

Disconnect the End of the Fuel Return "Cigar" Hose put something under it to capture the Fuel. Once the Engine is running momentarily clamp off the returning Fuel. You are checking to see if raising the Fuel Pressure makes it run normal. If blocking off the return Fuel makes things better it is likely that your Fuel Pressure Relief/Overflow Valve is not holding fuel supply pressure.

It still could be that your Fuel Supply/Lift Pump is not working properly as there is 2 Valves inside of the Pump that need to work and the Hand Primer can be the cause of air getting into the fuel.
In the Service Manual there is a flow test and also a pressure test. Unfortunately there is no easy way to connect a Fuel Pressure Gauge and due to pulsation even a liquid filled gauge needle fluctuates.

If you have 1/2 Tank of fuel you can rule out the Fuel Tank Screen as the cause of the issue by swapping the position of the Fuel Return "Cigar" Hose with the Fuel Inlet hose where they attach on the Fender well. That bypasses the Fuel Tank Screen but draws fuel From a higher position in the Fuel Tank (if you drive with the hoses swapped it also means you will run out of fuel sooner then the gauge shows so only do it for the test).

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84 300D, 82 Volvo 244Gl Diesel