I picked up about 2 mpg on my '04 Yukon by "restricting" about 1/3 of the air flow coming out of the filter box by taping over the edges of the screen at that location. No matter what I do with my foot, only so much air goes in, so only so much fuel gets used. Perfect cure for leadfoots. Forces longer, slower acceleration.
Sure, I don't have ANY power, but every time I take the couple of pieces of duct tape back out, my mileage drops and I put 'em back in.
If you throw a check engine light or idle rough, back the tape of a tiny bit.
Enjoy your new underpowered truck.