Don't blame the metering unit too quickly, the black box on the side of the metering unit adjusts fuel pressure (and therefore mixture) based on information it gets from the sensors.... meaning you could have a duff air temp/water temp sensor...

Secondly, if you warm the engine up and unplug the wire from the 'black box' it will default to its set position, which should mean the correct fueling on a warm engine and NO BOOST.

Give that a go and let us know what happens.

Rob,