79 C20 350/400 2wd.
I had an issue with the holley I put on so i put the stock carb back on.
it was off the truck for only a few weeks with gas drained.

it sounds like its missing but i timed it with the hose disconnected and plugged at 8*.
still rough running. I havent checked the plugs yet thats next on my today list when I get the time.
this thing was running like a champ.
Any ideas on what else i should check?

 

make sure theres no water under the distributer cap

 

check vacume!

 

Vacuum, since you replaced the carb, suspect the carb base gasket for vacuum leak.