76 TURBO Z

They all fired. Some would fire together and some by themselves. I took off the intake manifold with fuel rail installed then cranked the engine to see if all my injectors where firing. I thought that the injectors would fire in the same order as the spark plugs 1-4-2-6-3-5

My 76 280z used to run great until it just randomly shut off. I've checked fuel spark new timming. I just recently removed the intake manifold to make sure all injectors are firing properly. I found that the fuel injectors are pretty much firing randomly. What can this be?