We had a 402 ls2 built for a C5 and upon first fire we're having an issue with what we believe is the injectors. Cylinder 1 and 6 the injectors will only fire once and the car stumbles to run. The other injector are firing as they should and there is spark. We thought it could be pcm related so, took out the pcm and put it in another C5 and it ran fine in the other car. WTF is going on? Why would 2 injectors not work? Worked fine when we pulled the motor and now not. Any thoughts?