1994 GMC C/K SUBURBAN (GMC) Engine And Engine Coolingengine Problems

THIS OCCURS ONLY DURING HOT WEATHER, AND ONLY AT HIGHWAY SPEEDS. THE SUBURBAN DIES ON THE HIGHWAY WITHOUT WARNING. THIS HAPPENS WHEN THE OUTSIDE TEMPS ARE 90 DEGREES OR HIGHER. AFTER WAITING 10-15 MINUTES ON THE SIDE OF THE ROAD, THE CAR WILL START AND THE TRIP CONTINUED. I'VE TAKEN IT TO SHOPS AND THERE IS NO COMPUTER CODE TRIGGERED. I'VE REPLACED THE FUEL FILTER (INLINE) AND THIS DOESN'T HELP. (I DON'T HAVE THE OLD FILTER). THE SUBURBAN ONLY HAS 65K MILES ON IT AND PASSES SMOG AND RUNS FINE OTHERWISE. THIS IS A HAZARD AS THEIR OFTEN IS NO EASY EXIT FROM THE TRAFFIC FOR A DEAD SUV WITH TRAFFIC TRYING TO AVOID THE HAZARD OF A CAR STOPPING OR ABRUPTLY SLOWING ON THE FREEWAY. SOMETIMES THE FREEWAYS ARE 6 OR MORE LANES WIDE IN EACH DIRECTION SO GETTING TO THE SHOULDER IS EXTREMELY HAZARDOUS. *TR