Engine miss

[Gapvalley]

I followed the video when rail pressure comes up I cut the key off. Pressure falls off instantly like less then 5secs. Used a block off tool on the rail capped off each injector and performed the test over with the same results. Rail pressure relief valve was replaced not long ago for this same code. Truck had all 6 injector put in 2 year ago. High pressure fuel pump makes a lot of noise when it ramping pressure not sure if this is normal or not.