So the reason for no spark was your voltage drop was below 11 volts, enough to crank the engine but not enough for the ecm to fire the plugs.
I may be having the same issue with one of my 5.7 MPI's. I'm wondering if a bad starter could cause this. The engine seems to crank at a decent speed, but my spark appears weak. Voltage at coil drops to about 10v during crank. All connections are clean and the battery has been recently replaced.