I had a 1978 F-150 Custom that had the same issue. Mine was carb'd and had the 4.9 straight six in it. Never the less I'll try to help with my Ford back ground. Many fords I've worked on (including mine) have all dumbed down to the same problem of bogging and stalling while driving. Fuel pump. Ford is has a common issue putting junk pumps in their trucks. I gave mine a good bullet proof fix and preventive action of:
1. Replacing fuel pump
2. New fuel filter (mine was inline so easier said then done on some trucks).
3. New fuel Pump gasket (if yours is on the side of the block, I'm not sure if there's a gasket on the actual tank if yours is located there).
4. Lastly, all new fuel lines.
I hope this helps and you can get your truck running better!