A couple different things can be going on here.
First, your no start with no fuel pump running - you do have a Passive Anti-Theft System (PATS) on the truck that uses a programmed key to allow the car to start when it communicates through a transceiver to a module that recognizes it.
If your PATS system is stopping the Explorer from starting, it will allow it to crank, but will not allow fuel pressure, etc. The tell-tale sign on whether PATS is an issue is the THEFT light on the dash. If it is solid on when you put the key in- , then there is no PATS issue. If the light flashes with the key in and in the on position, then you have a system issue or key issue.
P0171 - P0174 - bank one and two lean codes - can be caused by a few things. First, if you have low fuel pressure overall, these codes could come on. Beyond that, these 4.0L V6 engines (SOHC version) are known for leaking intake manifold o-ring gaskets, and that will throw the codes. You could also have a mass air flow sensor out of range, or some other vacuum leak.
Hope some of that gives you some clues. Write back if you have further questions. Good luck!