Sigh. You want this:
The complaint is my 4x4s mpg stinks but I want s 4x2 pre running truck that gets even worse mpg.
My understanding is that a new, custom pre runner truck is in the neighborhood of $150,000.
If you want a 2x4, trade your 4x4 in and get a 2x4 truck.
Because you'll wind up with a old 4x4 turned into a 2x4 truck with a shedload of error codes and idiot lights on the dash if you don't and the resale value of your converted truck will be less than a factory 2x4 truck.
Not worth the time or effort.
It is kind of like wanting a sports car but building a fast truck instead: compared to the same effort put into a sports car, the fast truck cannot go, stop or steer.
Its like buying a bad piece of real estate and overbuilding: no matter what the value of the overbuilt property is capped.
Don't do it.
Go back to the Great Pumpkin and get a new battle plan.