Check the temp sensor II for correct resistance values.
Check the wiring for continuity by the pin checks at the ecu wiring harness.
Check the ground for corrosion loose connections.
Check the plugs for proper gap.
Check the CO levels for proper CO adjustment. (You prolly can't do this one)
Check the timing for correct adjustment.
Check the AFM for bad contact between the wiperaarms and the carbon track.
(Check at pins on the back)
All this stuff is in the Bently. Don't have one? Get one.
Prolly not the ECU, though.
Later,

Dave & Sherrie
Williamsburg, VA
           zzzzzzzzzz__
         |E[__] [__]|[_]\\
         | _DC&SP | _ ||
* * * =-( )---------( )--=