1995 Riviera Stalls Out

I have a 1995 Supercharged Buick Riviera with approx. 124,000 miles. It runs and drives great, except that it always runs at the 1/2 way temperature mark and the cooling fans don't always run, especially when the car idles. The car's temperature will climb past the 1/2 temp indicator on the dashboard when in heavy traffic and then will just stall out. It will not re-start and I'm stuck in the middle of traffic until it either cools down or something re-sets. I do notice that this problem happens more often on warm days as opposed to cold days. It has been to various technicians and they have not been able to solve the problem, although some of them have witnessed the temperature climbing during idling and the cooling fans not running unless the air condition is on. Would anyone have any advice as to what it may be? Please help.

When it stalls, someone has to check if you have spark/injector pulse, if not the crank sensor is the " most" likely culprit. A scan will see if the fans come on at about 222 degrees, then if not, additional diagnosis is required.