hi, My 2001 gt mustang is not running well. 1) it did not start without holding the gas. Cleaned the idle air control valve. It helped. 2)But,it feels like it is not firing on all 8. I pulled all 8 coil on plugs and checked for continuity between the primary side of the coil pack and the secondary side of the coil pack. The primary side on all 8 reads on specs. Secondary, 6 coils read on spec 5.5 and two coils read 5.3 below spec. Can is reading on these coils below spec cause a missing firing? I am not getting error codes. One coil on plug boot with correct spec has cracking at the end that connects to spark plug. spark plugs (E3) are clean about 70,000 miles on spark plugs. By the way 134,000 miles on my mustang gt. That is as far as my check list has gotten. Next checking injectors.