PLEASE help me! VNL670 with an ISX CM2350 4.4 MPG!

[VNL670]

I did notice that after every PARKED REGEN I do, I get slightly better fuel mileage from 4.5 MPG to approximately 5.3 MPG. Then it starts to drop back down.
Here is what I am doing next week at the shop:
1. Overhead valve adjustment.
2. Fix the oil leak from the valve cover.
3. Injector leak test.
4. Pressure test the CAC.
5. Check turbo doser for leakage.
6. Check SCR for clogging.

I will keep you guys posted on the findings.