Sure does sound like slipped injection timing. As ngoma said the timing check will provide the critical info you need.
Even just a rough visual check of injection pump timing using the external timing marks on the IP and flywheel might give you a hint as to whether your issue is in this area.
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86 745 D24T/ZF 345k lifted 2.5"
83 764 D24T/M46 155k
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