Lift hurts milage (more air going under the truck).
Big aggressive tires hurt milage. A cap on the back
hurts milage. Going fast hurts milage. Not adjusting odemeter readings for larger tires hurts milage (becuase your odo says you have gone less distance than you really have)

Stock my truck (similar to yours 94 xtracab, 5 speed, 4.1 gears, 225 tires) got around 20 mpg (I think my best tank was around 25 - mostly downhill at 45-55 mph - that might have been after a put a tonnue cover on the bed which helped milage a little bit).
Putting on 31" swampers brought that down so if I got near 20 I was happy (adjusted for gearing). Taking off the bed cover, and putting on a cap made me happy if I got 18. Putting on 33" BFGMT and now I'm happy if I get 16 (regeared to 4.88 now, so assume the odo is about right again).
Keep in mind that as time passed I also started carrying more weight - highlift, spare parts, skid plates, rock sliders, heavier bumpers, winch, etc. I still keep an eye on my gas milage, it can be a useful diagnostic tool, but as long as I'm above 15 I don't worry too much (unless I've been wheeling alot on a tank, then 10-12 is not unreasonable)

Sounds to me like you are in the ball park. To get better milage put on small highway tires, and keep your weight as low as possible. Also keep your speed down. Sounds like fun huh. I like getting decent milage, but, if it was my primary concern I'd be driving a small econobox. Luckily I walk to work most days so don't really worry about it too much <img src="/forums/images/graemlins/kewl.gif" alt="" />

Murphy dictates that once you put that tailgate down, you'll smash it. <img src="/forums/images/graemlins/shame.gif" alt="" /> The sheet metal shell by itself runs around $170. Leave it up; I see no difference in my gas mileage, and like what Thief said, you're running about par. Tire pressure should be what's on the doorpost of the truck. Depends on your weight with mods, etc.

That can hurt gas mileage and power because it screws up the air flow. The stock cat is restrictive, but not because of the matrix in it. It's restrictive because of the small openings and the sharp angles it makes flaring out to the size of the matrix. One of the cheap performance cats from Summit will perform better and cost you less.

On my stock 2x4 1-ton, I get about 22-24mpg average, driven about like you drive yours.

I swear my gas mileage got worse after I hollowed the cat, but I never checked it officially before removal. I just ordered a catco free(er) flow unit off Summit for $112 delivered. The empty cat was too throaty for me anyway - i.e., too throaty for a slow truck. I like the sounds of 22-24 mpg, but that just doesn't seem to happen on the 4bys. Too bad. I'm ready for a deisel. I've slowed to 65mph on the highway for this tank of gas - I'll see what that does.

Yo! I don't like your math. <img src="/forums/images/graemlins/wink.gif" alt="" /> I'll give you a max of $300 in gas costs (2200miles/14mpg*$1.80gallon). I guess it won't be any lower than $230. (I'll sneak the heavy stuff into my girlfriend's cherokee) <img src="/forums/images/graemlins/kewl.gif" alt="" />

Still learning how to use the board. This post is in reply to a post 8 posts up!

I didn't know the distances, so I guestimated 2500 miles, instead of 2200. <img src="/forums/images/graemlins/rolleyes.gif" alt="" /> That would change it to:

14 mpg for 2200 miles, at $1.75/gal = $274.99999 ($275). <img src="/forums/images/graemlins/cheers.gif" alt="" />