This fix works in the latest release - GTA 4 Complete Edition (2020) [v1.2.0.32], as well as earlier versions of GTA IV [1.0.7.0] and EFLC [1.1.2.0]
This mod removes the ammo limit for original weapons. For example: you buy 100 missiles for an RPG, but after saving and reloading the save, you only have 8 missiles. The fix sets the maximum ammo limit to 9999 and fixes their decrease after saves.
!Don't forget to back up your original files!
Installation: Replace "WeaponInfo.xml" files in GTA 4 and Episodes, which are stored in: