Update on extreme lean condition during boost

[Joel Skousen]

Thanks for all the help received so far.  

Done so far:  WOT checks good
                        New spark plug wires--does not seem to be missing at any time, even under boost
                         Checked fuel flow rate as per Bentley, at the return line for 30 secs:  760 cubic centimeters at 12 volts (right on spec)
                         All idling and rev  fuel pressures up to spec

Problem still persists: 
    My electronic richness measuring equipment shows it going very lean upon any acceleration, but it quickly recovers into normal range if I keep the acceleration moderate.  When above 3,000 RPM going into strong boost, it stays extremely lean, engine knock sensor light comes on showing full retardation, and engine falters from lack of fuel.   It appears that the fuel distributor is not accommodating the computer's call for more fuel at  boost above 1 bar.   Any other suggestions before I replace the fuel distributor?  

Joel Skousen
3 Audis.