From TCM manual.  For turbocharged engines...."An integral aneroid valve functions to increase pump output pressure during high manifold pressure operation."  If the upper deck reference line was leaking and suppling the pump with a low value, the fuel rate would be reduced. However, both banks would be affected. I don't know what would affect just one side. You also would see the reduced WOT fuel flow assuming you have fuel flow displayed.

Craig Berland

N7VG