Not so good gas mileage?
 

I've got a buddy with a mid 80's cougar with a digital dash and such. Want to say same engine as my 90 fox and he ACTUALLY gets about 15mpg city. It has an automatic and is completely stock. I'm in the same boat just have a t-5 and I feel as if I'm getting way less than that. Maybe 6 or 7 miles to the gallon. To me this is horrible. Emissions were removed from my car but the EGR is still hooked up? Checked all spark plugs and they are nice and white. Has new wires. Flowmaster catback system. A few did suggest I do a fuel pressure test and that I replace my 02 sensors. Just have been working on a few other issues that are now fixed. So what's normally the main cause of such horrid gas mileage?
Engine has approx. 93k miles on it. Was rebuilt sometime ago however.

Your right foot is the usual cause. What RPM do you usually shift at? Spark plugs are supposed to be more of a brown than a white..... how many miles do you get to a tank?

The Driver...

My 347 gets better mileage than that, and I drive the **** out of it.

replace your O2's, clean your maf, and set your timing.

That's insane. I get 25 highway at 80 with 3.90s and 18 city with a lead foot... And white plugs is lean isn't it

Wow. I must be doing something incredibly wrong...I get 19mpg at best on the highway with 4.10s and 15mpg in the city...

I have a 2v..... That's about right for a 5.0

yea, I think you are. I get that kind of mileage with my 347.

I was getting about the same as everett when my car had the stock engine in it.

Yikes! !!!! I drive like a old lady in a Lincoln. Seriously. Shifts rarely rarely see 3k. All of my plugs were white.

O2's here I come! And maf, and timing.

I'm getting just over 100mpg on a full tank.

sounds like my car, can't get it above 18mpg on the highway and goes between 9 and 13 around town 9 being me driving the piss out of it and 13 the other extreme. O2's are next on the list when I have the currency to spare, other vehicles are draining my funds. btw, I run premium on 15-16 degrees advance, and adder i know your thoughts on octane and you don't need to recite them

Thats pretty horrible too because I better than that with my carbed 306 with its cam that sucks gas at idle...