To me it seems like it has to be a fuel pump condition or calibration issue. I'm sure this is not what you want to hear, but I think your best move is to remove the injection pump and bring it to a certified local Bosch fuel injection reconditioning center and ask them to run the pump on their test bench. It should not be too expensive and at least removing the pump is relatively easy with the engine still out of the vehicle.
__________________
86 745 D24T/ZF 345k lifted 2.5"
83 764 D24T/M46 155k
|