i take it that all the ducting and pipework is in place from the metering head to the inlet manifold,if there is any leaks where air can get in between the metering head and the throttle butterfly no vacuum will be sensed by the sensing plate in the metering unit and no fuel or very little will flow to the injectors as its air flow that determins fuel flow with this set up
you could try this,take the black inlet ducting cover off the metering unit and look at the sensing plate, try lift it up but be very gentil as its a delicate piece of machinary if all is well then while holding it up fully crank over the engine with an injector pipe disconnected and see if fuel comes out,this should simulate full throttle fuel flow, but BE CAREFUL and dont set youself and the car on fire put the pipe into a container or something.