New head, low oil psi, 50% jake

[JasonD5746]

Cm2250, 530,000mi, egr tune
Bought w250,000mi only time cover was off since I've had it was for overhead at 275ish
Just replaced head for leaking injector cups, reman head new valves used old rocker assemblies. Now, low oil at idle (15psi), jake only doin about 50%(maybe).
Wont hold truck back bobtail on high. Had another mech same shop run overhead, he used cummins tool for Jake's. Ohmed solenoids, both at 9.75. They changed oil, put in 10/30, I drained it put 15/40 . Jake makes different noise in all 3 settings, but now level 3 is more like level 1was b4 the work.

What could have happened/ been done incorrect to cause a drastic change like that..?

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