85 f150 4.9 4 speed new carb bad mpg?? Help?

[85Beast6]

So I started driving my f150 again. I need to haul tools and material for work so I've been driving it daily and it's costing a lot on gas. Average is 9mpg and around 130 miles between filling up the tank. I've tried driving it very gently and mpg doesn't change. Before I started driving it again it sat for a couple years and was only driven once in a while inbetween needing new parts. I had taken it to a shop at one point and they replace the carb with a newer one but it felt like it runs rough still. Also I need a muffler. Could that mess with the fuel economy? The exhaust ends after the 2nd cat. I would like to continue to drive it if I can figure out the mpg problem. Thank you

[B RON CO]

Hi, you have got to check the whole tune up, from is the air cleaner good, choke opening all the way, spark plugs clean, not black, ignition timing.., vacuum advance working, ..... to clogged cats. Look at the easy things first, but it could be anything, even stuck brakes and low air pressure in your tires. Good luck