Car stalling

My car has been stalling on me whenever I come to a complete stop, either at a stop sign or red light, even in traffic on the high way. I have had it checked by three different mechanics, one being GMC, and they have found nothing wrong with the car. I replaced the battery thinking that was it and still nothing. I cannot drive this car because it is no longer safe but I cannot fix it because no one knows what is wrong. They say it is fine and does not stall on them. I have had four other people drive the car and it stalls on them. I do not know what else to do.