I still think it's an injector problem, but I agree that it's probably electrical. That's why I wanted you to check with the noid light. I have a hunch that the drivers in the ECM for 1, 2, 6, & 8 may be bad, leaving the injectors open at all times, rather than pulsing them. If the noid light didn't pulse for those injectors, but just stayed lit, then that's what was (is) happening.
Anyway, good luck with your new project.
Take care,
~Chris