Electrical? Alternator? Battery?

For the past few weeks my ‘97 Diamante's alternator and brake lights have been coming on and off simultaneously. I was going to take the car in the shop one day before the car completely died on the freeway. Off the bat we all thought it was the alternator, and machines showed it was... I replaced the alternator yesterday and the lights are still coming on and off. What can this be?! Please help, any suggestions or warning signs will be SO HELPFUL!!! Thanks!
-fyre

i just read your post, well i had the same problem with mine, i got the alternator changed, and the alternator belt changed and the lights went off...
if u did change everything, i am guessing its a glitch ...
but i would like to know, if its gone? and how..