Electrical Issues with my 87' Chevy Caprice Station Wagon

One night i drove my car home after work and it ran fine, The next morning it simply had no battery power, Not even clicking.

-I took the battery to get it tested- A-Ok
So i put it in the car to check and it ran the car just fine for 2 trips to and from work, the 2nd night the headlights went almost completely out on the way home.
-Replaced the Alternation- still not charging the Battery
-Replaced the Started based on some advice that if the starter is weak it could be using to much to start the car

Now when I get the car jumped off the engine sounds great when I give it gas, drives just fine, If i turn on the headlights it almost completely kills the engine. once they are on if I give it gas it sounds like its back firing or sputtering once it hits mid RPMs. Anything I do that required Electrical power makes the car almost die. I’ve unhooked my radio a few weeks before this started because it would come on and go off randomly.

I’ve now been told to look in to a Voltage Regulator and/or look for shorts in my wiring.

I need to know if those sound like valid steps and how to check for shorts? Any other advice of suggestions would be great to have also.

Thank you.

Your battery has the side mount battery cables. If this were my vehicle, I’d replace the positive battery cable assembly.

Tester

Consider it done. Thank you so much for a very quick reply.