1983 chevy suburban carburetor wont pull fuel after idling for 2 minutes

was run after sitting for a year. I timed it and got it running good. After about a week, it died on me and I thought the mechanical fuel pump went out. I replaced it and it fired right up. It started doing this thing where I can drive it fine in the mornings but it will idle for about 2 minutes and die after work, (intermitenly). It then wont start back up until the next morning. It just will stop pulling fuel. I have already confirmed pump is good, tank is not going into a vacuum and filter is good. A fellow tech rebuilt the carb for me and I am sure this is not the issue. For some reason, the pump wont pull fuel till the next day! This is frustrating enough as I am mechanic at a local shop. Can anyone suggest anything? P.S. I pulled the tank down today and verified no blockages or plugged vents. It ran good then acted up.
Oh! this thing is all factory with 78,000 original miles (Quadrajet)

Pull the tank, blow out the lines. Probably has rust in the lines that block the fuel.

There's a needle and seat in the quadrajet carburetor. Check if there's a biton needle in it. If so, it will block the fuel.