Please Help, 79 Chevy PU 350, no power under load when warm
 

I just lost my husband and am trying to figure this out now on my own since he is not here to work on the vehicle. I have a 1979 Chevy Scottsdale Pick up, 350 engine that has low original miles, all original motor. Drives awesome & lots of power but recently when warmed up (10 min) it cuts out when pulling hills or giving it a lot of throttle. Almost like not getting gas... But if i throw it into N & rev it up...It stops cutting out. Had a guy at Cost Less auto parts tell me to try the ignition module under distributor... did and it is not. ANY IDEAS? My ONLY vehicle. Thank you

Possible fix
 

I'm so very sorry to hear of your loss. I admire your courage, you got this one girl. To me It sounds like fuel starvation it could be vapor lock but I'd start with the fuel pump ( since it pumps more at higher rpm & you said when you reved it up it resolved) and the fuel filter in the fuel line. There is also a filter in the carborator right where the fuel line enters it. You can also try removing the gas cap when the problem occours and listen for a hiss like there's trapped air. This is unlikely but vapor lock does occur in the tank if the vent gets clogged. Good luck and please Let me know if this fixes it for you. Gotta keep these old square bodies running.
Sean