I read the stuff below at the Callaway website when I saw your post. I got to this part about the Microfueler--"With the exception of relying on the fuel pump for pressure and the tach connection on the distributor for engine rpm it is 100% independent of the car's engine control system" and quit reading since it sounded like the Microfueler doesn't control boost condition. I am still a little curious as to how the Microfueler failure caused boost to go down. I would have guessed--as they say--you would simply go way lean and damage the engine. Oh well...glad you got it fixed.
"The next thing to look at is the "Microfueler" system. This system consists of the additional injectors mounted on the "rams horn" (the casting in front of the throttle body), a black box, a wiring harness, and a fuel hose connection from the fuel rail at the intake manifold. This system is there to provide additional fuel to the engine under boost conditions only. The injectors are driven by the black box mounted on top of the kick panel over the drivers knees. This box senses engine RPM and manifold pressure, and drives the injectors accordingly. With the exception of relying on the fuel pump for pressure and the tach connection on the distributor for engine rpm it is 100% independent of the car's engine control system. Failure of this system will cause a lean condition in boost that will at a minimum make the car feel down on power, and at worst will cause engine misses and/or detonation. Another possible failure with this system can cause it's two injectors to be held open constantly when the ignition key is in the run position. This will flood the engine and cause a no start condition. If disconnecting the electrical connectors at the injectors enables the car to be started than there is a problem with this system."