Put a 318 in there. Seriously I've had more Dakotas than I care to remember. Best mileage for the V6 ones I've had was my 90. I've had 92, 93 and a 96 all with 318s and except for the 96/ which was also the only 4wd of the bunch/ as well as the only one without 3.55s, and every 318 Dakota I've had had been better on gas than any of my V6 ones
And the 96 was no worse on fuel than any of my 2wd V6 powered ones were ..
I converted the 93 to a stick and it was by far the best one I had for mileage came from the factory with the 318 and the 3.55s, I put in an nv3500 in place of the dead 518 that came with it when I got it, it was rare not to get at least 20 mpg with that truck. I miss that one, but I wrecked it back in about 2016, way beyond fixing