1986 Dodge Truck 318ci Runs Fine While Driving Losses Power Again

What loses power, the engine, something in the electrical system, power steering? If it's the engine, does it cut off completely momentarily or just act like you let off the gas pedal a little? How long does that last, a few seconds or does it stall and not restart until it cools down, often as long as a half hour? It's easier to know the details and observations than to guess at all of he possibilities.