Gauges/lights on instrument panel sporadically flicker off and on and the car stalls

All gauges/lights on instrument panel sporadically flicker off and on. This occurs while idling and driving and it occurs almost on a daily bases. Car didn’t drive noticeably different at first, but lights and chime kept alarming. I change the oil and fluids regularly and I have had my fuel injectors and other regular upkeep maintenance on my car. The check engine light isn’t on so of course no codes are showing up. On several occasions while driving on the highway or the street the lights did back-to-back flicker, all gauges zeroed and car begins to decelerate. Could not accelerate but within a few minutes the gauges and car powered back up. However, when I am on the street I can safely pull over and restart the car. It’s a rather scary while I am on the highways (especially during rush hour). So what is wrong with my car? When I had talked with the guys at AutoZone they said it was either my battery or my alternator; I have since replaced my battery and I am about to replace the alternator but researching this issue it seems that is quite possible that it isn’t the alternator either.