Headlight blink on and off

Does it do it with or with high beams?(NOS) 8)

I think the problem is a real bad short, the key words you told me was the battery and the alternator have been replaced twice. There is something shorting these thing out. First do this take the knee panel off under the steering wheel and check to see if there are any burnt wires or switch or any thing of that sort do this first. Were going to have to take this one step at a time. For the simple reason if something is taking out both alternator and battery that explains why the car dies and the lights go out, cause there is no voltage to run nothing. If you loose the alternator the battery would run car till the battery run out of voltage but not both.(NOS) 8)

There is one way for both to go out but not within a couple mins. If the battery goes first which actually can happen the the alternator will strain and work 2x over time to "charge" the battery causing the alternator to short, but if problem keeps occuring then follow NOS suggestions. 1 STEP AT A TIME but when you changed the alternator make sure you put it on a fully charged battery.