Try this. Cycle the key on/pause/off several times. Do not crank. Listen for the fuel pump to run each time. Does this improve starting?
If so, suspect either a weak fuel pump or fuel pressure leak down.
The battery terminals really need to be clean, corrosion free, and tight to get the most from the battery.
2003 GT Convertible (sold & missed)
2000 GT coupe (Craigslist project. Fixed. Now my DD). Windsor to Romeo swap.