No power. Poor fuel economy.

i thought 5 mpg was good for a working truck i am currently averaging 60 litres per 100 km just to confuse you hauling 64.5 tonne. anyway getting back to your question of lack of power its a process of elimination start at the bottom and work your way up although they should have a usb plug in that should be able to trouble shoot any problem on the computer analysis check the fuel filters bad fuel will clog up the fuel lines and the injectors causing power loss also very important check your air cleaner a clogged air cleaner filter can significantly reduce you power.

 

Could you have gotten a bad tanks of fuel? Sometimes the tanks at old stations start getting a mold in them that is not good.

 

If you get it in your lines and circulated into your system it starts growing and becomes out of control, its a dark green looking gunk I floating in the tanks, stay away from them places that let the tanks get almost empty before getting another load.

 

Got it in a reefer engine once, trashed it

 

It's more likely you had bad fuel and damaged something else than fuel lines. In this case, nothing is impossible.
But there are two major enemies that kill injectors: water in fuel or air in the system. Considering, the fuel filter had the required micron rating.

Why would the dealer want you to change the fuel filter base? Just to sell you another costly part? Did they diagnose/verify the fuel pressure?

Do you have a Davco fuel filter installed? If so, check the plasic(glass) bowl for cracks, the cap and O-rings. A normal level of fuel is just above the collar.

I'm sorry to hear about your ID theft. But sometimes it's necessary to make a step backwards and start over again.