89 pathfinder problem help

While driving I hear a "pop" sound and suddenly the engine got louder, started to shake and rattle. I pulled over and the engine die on me. started the car again with no problem but engine die again if i don't accelarate. New battery. When the alternator goes out does it gives out a "pop" sound? Belt appears to be fine. If the alternator is not working does the engine shake a lot more? or could it be something that got loose or disconnected? like a bolt? How hard is it to change the alternator? sorry for all the question. Any help would be greatful, thanks.