Need recommendation for a Carb for better MPG!

Depends what mileage we are talking about, intown vs highway or some mixed version.
Where I live 15-20 mins (good traffic) outside of Toronto, I could go my whole life without taking the highway it's like 5% or less of my driving and when I do it's very short amount of time 2-20 mins.

Intown Unless something is wrong with you car it's gonna be hard to improve mileage in any significant way it's just gonna take a certain amount fuel to drive a A body sized car around town. Of all the different cars I've owned most got like 15-17 intown, worst was my 5.9l Jeep at 12 mpg and my Avenger R/T 19-21 mpg is the best I've had.

Highway you could do decent improvements but you really have to be putting a ton of miles on to break even on a lot of mods.

Seems like in America the highway is more apart of your lives.