1991 Buick Century Stalls at times

Mine does the same. I don't know how to fix it, but notice the weather. Mine runs great at night or cooler weather, and only last about 10-20 minutes in hot weather. I got new radiator and thermostat and flushed the cooling system. Fan kicks on then 2 minutes later car shuts off. Mechanic said it gets to 220 degrees and shuts itself off to prevent damage. Some safety precaution. It's a bunch of crap if you ask me. But I think some sensor is telling the computer its hot when it really not, therefore shutting itself off.
If you figure anything out let me know please vice versa.
Thanks!

My Buick does die more in the heat than at nite, but starts right back up as if nothing ever happened. No idiot lite ever comes on and it only happens when I come to a stop. As if it does not know when it has reached the idle speed and continues to idle down and kills its self. I re-fuel when I reach 1/2 a tank and use ijector cleaner as well, even after it dies and starts back up it runs like it had a fresh tune up not a sign of a miss any where. To diagnose the problem I was told it wold have to happen when it was on the machine and I never know when it will happen. Some times it runs for days just fine. I have thought of changeing the fuel filter but have no clue where it is to change it as some times it will feel like it is starting to surge as well. If I figure it out I will let you know and thank you for your idea as well.