I am gunna say its low fuel pressure. Because it starts and runs well, its not compression or injector. When trying low speed, the fuel pressure drops causing fuel to just dribble into the cylinder without igniting. After several non firing strokes, the raw fuel vaporises from cylinder heat, causing ignition on subsequent compression, then the cycle continues.
Years ago, a dude fitted a new fuel pump to his toyota Hilux. It needed a tow start, and then would run hot with no power. Turns out it was injecting on the intake stroke, burning vaporised fuel rather than atomised fuel., so this is certainly possible.
Injector pumps should have constant pressure, and variable quantity. Veggie, I would loosen the injector pop pressure to see any change.... if its a fuel pressure problem then it will have little effect. Mind you, it has little effect anyway that I have seen. Setting the rack at a low speed and testing removed injector spray by cranking may point to the problem.