While driving my van the radio randomly shuts off, dashboard keeps flickering?

I need help fixing something
Last week while driving my van the radio randomly shut off. Then it started doing it only when I braked. That lasted a couple of days before my car would shut off while in park. It would immediately come back on. Now my car is shutting off while idling at a light. It has always come back on except one time where I had to put my car in park and re start it myself. The lights on the dashboard also keep flickering. I've checked all my fuses and they're fine. I've also checked the battery and alternator (both new) and they are giving off the proper voltage. This thing is almost paid off and I'm barely making ends meet so I can't afford a new one. Anyone have ideas on what's going on or what to check?