CM2350 fuel rail issue

[ktblogistics]

so have some codes for injector solenoid driver and turbo
for turbo inspected and replaced crankcase filter for maintenance free
(looked like clogged to full capacity)
replaced intake manifold pressure sensor
replaced exhaust back pressure sensor and check tube for clogging
both sensors were painted red so might be original with 750k miles

did fuel leak test and pressure dropped to 100psi within 16sec
so from 30k to 100 ,tried it few week before also
it drops like a extremly fast

did fuel amount test and had 100ml for 1min at 30k psi
used cummins tool at return line from block

what else i can do to find a solution or do i do something wrong
truck is demandated
thanks for your help