A tune up would do wonders for your mileage. Be aware that a 25 year old car that hasn’t been run much will need a major tune up to be dependable. The usual stuff like plugs, plug wires, distributor stator and cap, air filter, PCV, timing check, and more than likely a carb rebuild or cleaning. Also replace any vacuum lines. Those hoses can have small leaks that will drive you crazy, best to start anew.
Something peculiar to Fords is the aggravating tendency for the old coil and the dura spark ignition module to intermittently go out when the engine gets hot. I had to do a roadside replacement because of this issue and wish I had replaced them from the beginning. They are not that expensive, (around $35 for the module and $20 for the coil and available at AutoZone) easy to change out and well worth the peace of mind.
Once this was done on my Duchess I am consistently getting 23mpg in town and 27mpg on the open road. And I don’t exactly take it easy
If you don’t have the DuraSpark module (most 2.3s have them) I can send some info on hooking one up. They are very much worth putting on and will increase your performance and mileage.