Fuel Injectors + backfiring

What will cause fuel injectors to lose there electrical ? This randomly occurs,
engine runs great ,untill this backfiring starts happening mostly from #1 & 6.
Number 3 & 4 also acasionally misses a rhythem, I used a noid light and from
listening through a long screwdriver to find this problem. Please help me,

No pulse at these injectors with a noid lite on?, look at connections on your icm and pcm, try tapping the pcm firmly with a screw driver handle see if the engine responds, make sure you also have 12v to the suspect injectors the noid lite won't flash without pulse from the pcm but it also won't show if there is no power to the injectors.