When a load is placed on the battery like brake lights/fan etc.. while driving the radio goes out. Any ideas? Battery and starter just replaced happened right after. Regulator? It also rough idles

I saw this in the other thread. So, this problem didn't exist until you after you had changed the battery and starter? Are you sure that all connection are proper and clean? Until I hear more, it just falls under the mysterious heading of 'electrical issues'.

Sanded and cleaned all connections to starter and battery before I reconnected.

what about where the grounds attached to the chassis? did you check and clean those?

Did the grounds I saw engine and starter. Here is what hapens. Car runs and drives fine, everytime you turn on lights/flashers/apply brakes/fan/power antenna a draw happens. Then it clears and is normal..very fast! I did find out that the guy helping me briefly reversed the battery cables and got a quick arc. Battery is still good and I am thinking the regulator got zapped. Changing that out tomorrow. Car starts and runs.