Dying at idle?!?

I recently installed a dual carb weber 38 clifford intake and headers. My car kept dying at idle so I installed a new alternator as mine was shot and a new battery and voltage regulator. Car was fine until earlier today when I changed the belt for the alternator.

On my way home from autozone it stalled out 4 times. Every time I had to stop at a light or for a turn. But would start and idle and allow me to shift back to drive and be fine.

Now at home all it does is start up and I can rev it to kept started but as soon as I try to shift it dies.

Could it be the idle mixture?, an electrical problem?,

It's a 1972 duster 225 slant six.