are you having battery charging issues but have changed the battery and alternator? check the fusible links. the usually blow once they get corroded enough over time
Check these guys out:
Diagnosing Alternator Problems - EricTheCarGuy
https://youtu.be/FTGz0PKIl84
How to Test an Alternator - ChrisFix
https://youtu.be/LGB6ZEjGm7Q