My 95 V8 5 speed Dakota standard cab shortbed 3.55 averages 300 miles a tank-22 gal capacity. I got around 17 mpg on this truck, not bad considering how heavy my right foot always got when I sat in that truck.
My 93 V8 auto O/D Dakota Clubcab shortbed ratio? averages 270 a tankful-22 gal capacity. My fillups are usually 18 gallons so I get better than 14 mpg. I expected better mileage from this truck when I bought it, disapppointing.
I prefer the throttle body in the 95 to the injectors in the 93. I find the throttle body more responsive as well as more efficient.

Huh? Could you please elaborate?

I just took a 400 mile trip in my '93 3.9L V6, automatic, extended cab, stock - 22.14 mpg on the trip driving about 73 mph. I checked this with GPS and calculator. I'm happy with me Dakota.

Oh, I try to only use non-ethanol gasoline:

http://pure-gas.org/

Nice! I've noticed my '92 3.9L manual gets better highway mileage when I'm cruising from 75-80 MPH compared to 55-70 MPH. I have to verify with a GPS but when the speedometer has me at ~80 the engine's turning 3,000 RPM in overdrive which definitely helps on the grades and with passing, being 200 RPM right below peak torque.

They both use multiport EFI... Of course the 95 get's better mileage, it's a regular cab and a 5 speed.




Mine averaged 15-16 mixed and will do 20 highway.

Sorry for the confusion. I should have been more succinct. My research shows that both my 93 and 95 Dakotas have the same intake, throttle body, injectors, but utilize but different ECMs. The difference in performance, efficiency, and behavior between the 2 trucks is very striking. I expected a difference between auto O/D versus 5 speed and standard cab versus Clubcab (both weight and longer wheelbase) but I also expected a reasonable amount of similarity, or a pattern, to their behaviors. My 95 5.2L 5 speed is a thrill to drive, has alot of torque, and will sip fuel when driven conservatively. The only maintenance issue I've had is that it will begin to run at a rough idle from time to time. Some throttle body cleaner to the underside of the 2 round air flaps (unsure of the proper term for these) inside the throttle body solves that problem. My 93 5.2L auto O/D, on the other hand, is very finicky. Upon startup, anything resembling touching the gas pedal before reaching normal operating temp causes the engine to sputter and stall so warmup must include my assistance. If I loan the truck out, whoa, forget it, the truck will run terribly for a month and stall often coming to a stop. It's as if the computer must re-learn how to act/react to certain situations. Nothing I've done, maintenance or repairwise, has altered its behavior one bit, and yes, the IAC checks out good, no codes coming up either. I love this truck. It just has certain behaviors that appear if its routine is altered in any way. I didn't expect such a difference in fuel economy either, in fact, I'm much more conservative in the 93 so mpg gains would be expected.

I honestly believe that when dealing with vehicles of this age, wear and tear plays a bigger role in fuel economy in comparable vehicles than any other factor.
For example: My 87 cutlass got ~15mpg with the bone stock 307. It was a 150k mile motor with little maintenance before I got it. Similar cars got 18-22 mpg, and I could not duplicate that no matter how I tried. What it came down to was wear and tear on the major internal parts of the motor along with a failing computer system caused by degraded sensors and lack of care.
That's what your 2 trucks sound like, one faired much better over time.

'94 3.9 2WD, I'm getting 15 combined but its not running right.

So it seems like when the truck is running good, she'll get about 20 or so, and then when it's running bad it seems the average is 13 or so. I really want to drop in a 318 this year in hopes i'll get a little bit more power and mileage

I've gotten as good as 21 on the highway in my '95. My '92 and '93 both got around 15-18 on the highway. They were 4wd whereas my '95 is 2wd 5-speed. All three have 318's.