1992 Dodge Dakota 92 Dakota stalling

I have a 92 Dodge Dakota that I drive about 25 miles to work every day, about 19 miles of which are highway miles. The dakota will start & run fine, with nothing out of the ordinary going on. After I have gone about 5-10 miles down the highway, it often, but not always, will stall out & die. Once it dies, it refuses to restart immediately. The engine will turn over, but it just won't start up & run. If I wait anywhere from 5-30 minutes, depending on the day, it will always eventually restart. When it finally does restart, it always start easily & runs like normal, & may or may not stall out again before I get to my destination, but usually not. I have noticed that this only seems to be a problem when running at highway speeds at or above about 60 mph. It hasn't done this while just driving around town. It also seems to happen when I have been in heavier traffic, where I have been forced to accelerate & deccelerate more often. I have recently replaced the spark plugs, plug wires, distributor cap & rotor thinking these may have been contributing to the problem, but have not made any headway in eliminating the issue. Any insite you can provide will be appreciated.