Did you try working the rack back and forth through the shutoff valve mounting hole...?
Sounds like the rack is hanging inside ....(will have too remove shutoff valve to get to end of rack...
The shutoff valve has an (L) shaped end that hooks into the rack to pull it into fuel shutoff when vacuum is applied...
The governor controls the rack most other times.....
If it moves freely with your hand...then you know it is not binding internally...

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1978 Yellow 300D (The Mustard Toad)
1980 Blue 240D (The Iron Toad)
1989 Grey Mitsu.4WD Mighty Max Pickup (Needs a Diesel transplant bad)

(Open the pod bay doors HAL)