Back to the Thrust lever position: First sentence in QRH is objective to START AT LEAST ONE ENGINE.
In normal operation the FADEC will control the fuel flow according to the TL position.
http://www.boeing.com/commercial/aer...ly/sy01txt.htm
RPM Hang-up During airstart
During airstarts at high altitudes and low airspeeds, rpm hang-up may be experienced after obtaining initial light-off and acceleration. The hang-up is characterized as a stabilized engine speed lower than idle, with no response to throttle advancement and may be the result of either too rich or too lean fuel scheduling, low airspeed or excessive altitude.
The inflight start envelope defines the region where windmill starts were demonstrated during certification. It should be noted that this envelope does not define the only areas where a windmill start may be successful. The Loss Of Thrust On Both Engines NNC is written to ensure that Flight Crew take advantage of the high RPM at engine failure regardless of altitude or airspeed. Initiate the memory portion of the LOSS OF THRUST ON BOTH ENGINES NNC before attempting an APU start for the reasons identified above.