bad gas mileage

I have a pampered 1997 2.3 ranger. New plugs, wires,  camshaft position sensor, timing belt and tensioner.
Not showing "check engine" light. Starts good    runs good.    Good air filter. Runs smoothly.........used to get 18 and 19 mpg with AC running in town.  NOW IS GETTING 12.5mpg. Any ideas??????

Might want to recheck the timing belt thing.  If your fuel economy dropped after the service was done, it is probably a tooth off in time.  Will still run, just not quite as good.  The oil pump sprocket is also the timing for injector drop, if not set correctly, will affect fuel ecomony as the fuel injector is not popped at optimum time.

Also check your fuel filter.  The injected ford motors are very touchy about having clean fuel filters.  I changed mine at 42K miles and regained about 3 mpg.