Dying on me when A/C is on

So I have a 1996 mazda protege LX. It has had thousands of dollars in repairs already done on it. Almost everything has been replaced on it since Ive had it and it has always had a problem with shaking rapidly at a stop sign/stop light. It has gotten to the point where it will die if I leave the car in drive at the light with the A/C on. I usually put it in neutral until the light changes because it's just so annoying having it shake. But now that it will die while in drive stopped, I have to put it in neutral. Also it's died on my 4 times in the past week while backing up with the A/C on. I have to turn the A/C off to back up as well as while first driving off because it seems like its about to stall. Also the higher the A/C is the more likely it is to stall or just die completely. It's so frustrating. My dad is tired of putting money into it, so is this a big expense to fix and not worth it? I'm so over this car. Can you determine what's wrong with it from my description. Thanks.