1986 caprice classic with stock 305

i have a 1986 4dr chevy caprice classic equipped with a stock 305, well my car keeps on dying, i have a new alternator, starter and battery but still the dies does anyone no y this would happen i ha the alternator checked even though it was new and it was still good. any help would b appreciated thanks

and i tried three diffrent batteries they all were new

Define dying. Dying as in quits running while on the road? Dying as in a dead battery and the starter won’t crank the engine over?

From your post it sounds like you’re describing an inoperative starter motor. If that is the case does the starter motor crank very slowly, do nothing at all including no solenoid click sound, etc.?