any time she gets on the freeway and keeps speeds over 55 mph, after maybe 20 or 30 minutes the car dies and She has to coast for the nearest shoulder in the freeway then let it rest for about 30 minutes, then it'll start again
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I had this same problem years ago with a 1968 Dodge Charger. The problem was water in the gas tank. Seems the water had gotten in the tank with a bad load of gasoline. After the water sat on the botton of the tank for who knows how long it it started to clog up the in-tank fuel line access opening. When the car was on the freeway the suction from the fuel pump pulled hard enough on the bottom of the tank that it would pull the glob of water over the intake and cut off the fuel supply. The car would die....after sitting for 20 to 30 minutes the glob of water would recede from the intake, gas would go to the engine, and the car would start again. We found the water in the tank by using that grease-like stuff that turns red when it is in water. The solution was to remove the gas tank, completely clean it and remove some light rust that had formed. We re-installed the gas tank, filled it up with fresh gas.....and no more problems. I might add that when water sits in the bottom of a gas tank it becomes almost "jelly like"...that was what was restricting the gas from going into the fuel system to the engine.