V-10 Excursion missing; no code or pending code

carringb wrote:
A weak coil won't set codes until it completely fails.

That makes sense that the coil won't set a code as long as the PCM detects that it is firing, but if it's weak enough to cause a noticeable driveability issue you would think that the PCM would use its other resources like the O2 sensors to detect incomplete combustion or call it a misfire even if it doesn't know which cylinder..