Hi i have 77 f150 460 with motorcraft 4350 I rebuilt the carb today and it runs great but when its idling it acting like it wants to die and the idle is going up and down the person who rebuilt the carb before had stripped out the bottom plate screws so I rethreaded them that's what I thinks wrong with it I've pulled apart like 5 times now someone please help me

 

Could be a vacum leak, try spraying some WD40 at any likely spots and see if the idle improves