Well guys. With my new job it requires a lot of driving, so for economy reasons I've been driving my fiance's 03 Mustang, and she's been behind the wheel of my truck.

Unfortunately, she's fed up with the milage on it, and I can't afford to drive it daily. So I've been given my options

Either I find a way to get better milage for her, or the truck goes

It's a 99 Ram 1500 Extended Cab Short Bed 4x4, Auto, 5.9L
With 186,000 it runs fantastic, just can't get good milage out of it.

I've done some modifications (mostly for performance, but helps milage) but haven't seen much difference.
Magnflow exhaust, cold air intake, superchips programmer, and although I can't be sure she does, I've told my girlfriend to fill it with 91 octane (seeing as that's what I have it programmed for). I've tried programming it for towing and 87, and throughout all the programs, the best we've seen out of it is 13 mpg. Now I'm sure my Dick Cepek 33" Mountaincats don't help much, but I don't think that's the whole reason for bad milage.

I've heard people getting 15/16 which i would be thrilled to see, but since I've owned the truck, I've never seen better than 13. When I first bought it, I couldn't get better than 10 stock before the modifications. One thing I can think of, after 186,000 miles, could it be time for a new cat?

Need help before I'm forced to give up my truck.
Anything helps guys

 

thats actually good mpg's to tll you the truth. most here avg. like 9-10 mpgs. like you i am getting 13-14 city and alot highway (26 gallon tank 283 miles on half a tank all highway though) but ive put some dough into her. (195K 5.9 slt 4x4)

try getting an airgap intake,or get what i got, hughes plenum rienforcment kit. most likly yours is blown if it hast been changed. (look in tb for pools of oil)

and id say yes its abouttime to get a new cat and o2 sensors

 

I think the tires are probably the biggest problem. I use to have 33's and was getting around 10,11. After a tune up, intake, and seafoam before every oil change, and stock tires I get around 15. Thats with a 95 CC 5.9 2wd with 277,000 miles.

 

Ha well 13 is what she gets going to and from work, which is about 3 miles of city driving and 15 miles of highway one way 5 days a week. I've never seen good milage out of my truck, and my friend with an 01 V10 is getting the same milage as me.
I'll take a look in the throttle body tomorrow to see. Where do I look for the pools?

Sorry for all the questions. I can build older cars all day long, but newer stuff confuses me.

 

Hmmmmmmmm

Having some experience with women, marriage (16 years), divorce, jobs that required lots of driving (50k a year sometimes) and modded vehicles...and even though I understand that times change...
And finally, because I like thinkin' outside the box...

Son...take it from a guy who's been there...I don't think the problem is your truck.
And if you get rid of your truck, I can guarantee that someday a lot of other things may be gone too, including a couple of body parts. Don't worry though, when you get into your 50s, they're really a "drag".

But I degress.

My GF, who's been with me 5 years...just told me again today how much she loves riding high in my Ram. I reminded her how hot she looks driving it, and she giggled because some guy will always try to flirt with her when she does.
Then we took her Ranger to dinner, and she told me how much she appreciates me keeping it tuned and washed. I reminded her that I like the mileage it gets, and that its the most impresive Ford I've ever driven. I know she'd like to trade it off when shes paid it off for something a bit roomier, but I'm a bit cautious.

Out of courtesy, I always ask to use her truck, and she always reminds me we're a team, and I don't have to "ask"...but she appreciates it none the less.
I suppose some day I'll have to take the lift off of my Ram, as we're both gettting older...but again I degress.

Anyway, thats my nickels worth. Good luck son. Remember, I'm pullin' for ya...

 

I don't know your age, but I know mine. And after 35 years of "older cars" I don't know if I'd want to go back.
Complicated fickle carburetors, burnt ignition points, fan belts going everywhere, and smog equipment run by 400 vacumn hoses...no thanks!
Thats when we REALLY needed internet forums

And, despite the help and advice others have given, cleaning a throttle body, replacing your plenum, and dumping in an expensive can of seafoam every moon phase isn't gonna help much. I've done all that...and short of a tuner (which you have) probably more.
Smaller tires....maybe... MAP sensor? Worth a test. Compression check for leaking /burnt valves/ ring blow by? Might as well.
I think my truck got 13 mpg once...flat out 70+ mph, level ground, tail wind, tailgate down, cruise on, and no traffic. Otherwise 10. something to 11 mpg, day in, day out.

 

Mares, to get a good look you have to remove the throttle body. And be able to look down inside the intake. Bes way is with a small inspection mirror and a flashlight. You looking for any pooling or collection of oil inside the intake. But since you own a Dodge, and if you have never looked or corrected the plenum before, you have a leak.
.

 

Your friend with the V10 is lying.

 

Always such insightful input.

After fixing my plenum, replacing all my gaskets, getting rid of my vacuum leaks and not constantly putting it to the floor I went 320 miles on 20 gallons. But that is mostly highway driving to school and back (60 miles round trip). I try to keep it under 2000 RPM at all times.

 

They only pay me to be informative, not insightful.