Engine Dies While Running

1977 F-150 4X4 300 6-cylinder Inline 4 Speed on floor 118,000 miles Original Owner

After starting my truck and driving a short distance, the engine just dies. It starts right back up and it may do this once or twice and then runs perfectly. I have changed out fuel filter, spark plugs, plug wires, rotor and distributor cap. What can be causing it to just die and what should I check and do next to fix the problem. Thanks for your help
Dennis Wilson