I have a 99' dakota, with the 318. I think it works out to about 10mpg I get mixed city/highway, I like the gas pedal. Now im not complaining about fuel mileage, But I wanna tow around a 16 foot tandem axle trailer, I can only imagine how much worse my mileage will get running 3-4 gear on slight hills on the highway. I pulled the trailer empty yesterday, It gets the job done. Its high mileage engine 285,000 kms, Not miles. Engine totally stock, Im wondering if I can pick up a couple mpg's?? So I can be around 10 pulling the trailer.

I got a thrush muffler, Maybe I should get headers? Cold air intake?

What will help best for performance/ mileage?

I got a superchips tuner, maybe I should run 91 octane and that tune when im towin??

Just looking for suggestions on little more power, maybe mpg's.

Who tows with there 318's???

 

Depends on your terrain. I dont reg tow with mine but summer I do quite a bit. I've towed our 20 foot double axle trailer and does alright. Most I ever had on mine was 3,800 lb on bigger hills you could tell it was there but other than that it did great. Dont forget about trailer brakes will save some major wear. Anyway cold air intake and exhaust should help out nice. Anything to get more air in and out the better. I got a ebay cai(looks like k&n but has a fatter tube) for 38 shipped. Made a difference on the bottom end and I think gained about 1 maybe 2 mpg. Superchips has a tow mode have you tried that? 3.92-4.10 gears help out with city and towing your truck might have 3.92's if not they are 3.55's

 

I think I did try the tow mode, Sounded like timing chattered like crazy on hills, This was back with my 5x9 trailer loaded and back of pickup loaded. I ran 93 octane and 91 octane tune once, Truck seemed Alot faster. Maybe ill try that again with just normal driving, See if my mpg go up at all to cover the extra cost of higher octane. But for no chatter it does best with 87 octane on the stock mode. Ill get a CAI one of these days and see how it does. Gearing.... Im not sure what it is in this thing, Right now im runnin 20" rims and 33" tires. Mileage is exact same as my 31's and stock 15's and I didn't notice a power difference. I run 1850 rpm doing 60mph. Rpms just not change with tire size difference, But I can change the speedo with the superchip.

 

And are you talking 3800lb including your trailer or no trailer? I think my truck is rated to tow 6700lb