I was averaging about 300-330 miles a tank in the summer driving highways (64-75 mph) on a V6 2x4 01 Escape and have now dropped to around 200 up in North Dakota. I just replaced the Idle Air Control valve due to idle issues and that fixed that but still losing MPG's. Seems to be running fine but ordered new plugs and coils anyways.
I already bored out Cat #2 and deleted cat #3 so if the 1st cat was going or gone I would assume it would blow through the pipe. I figured some of the loss was due to Winter Blend fuel but 100 miles a tank seems a little extreme. The check engine light is also on and brings me to my next question of which OBD Scan Tools you recommend that won't break the bank? I also have a 06 Escape but isn't having any issues would like a scan tool that works for both. I have heard replacing the PCM and the MAF but not sure which route to go yet. Would rather diagnosis it before I throw more money at, granted MAF sensor are cheap. Escape has 72K on it fluids & filters changed regularly.

 

If you have a laptop with a USB port, you can get a scan tool for $20 or less, and the program is free. Search for forscan software. I think it stands for Ford Scan ..
There are many Blue Tooth units that plug into the OBD-II port under the steering column in the same ballpark. They will talk via radio to the Blue Tooth receiver on a laptop.
There are wired units that will plug into the USB port. The name ELM is one to search for.
You can spend more if you want a dedicated reader / scanner that does not need a laptop for keys or display. I think a reader that uses downloaded software is more easily updated and can add features that a dedicated reader normally cannot.
tom

added: the normal culprits to first check are 1)air filter, 2)spark plugs, 3)tire pressure, 4) thermostat and 5)fuel pressure regulator. IMO.