Need some help tuning

[Lonnon]

Long time reader first post. I have a 2005 Isuzu ascender that i just bought for $300 that needed coils (was running on 3 cylinders) i have got them replaced and would like to play with tuning, and help would be appreciated, i am thinking i need to do the following but i am not sure where to start:

1. Torque Management
2. Transmission line pressure
3. Transmission Shift Points
4. DFCO (not sure where to start with this or why it helps get better milage)
5. Want to bump the timing (but would like to use the 85 octane we have here in utah)
6. Smooth Out Spark Tables (I read this helps alot)
7. Anything else I am missing
8. Looking for max power but would like to get the best mileage I can.

I Work For Diesel Company and have played with Cummins Tuning but woudl like to get this nailed down.

Here is My 2005 Isuzu Ascender 4.2L 4x4 7seater stock file
2005_Isuzu_Ascender_4.2L_4x4_7seater_stock.ctz