vacuum leak at throttle shaft?

I messed with idle screw first. No help. I forgot to mention as I held throttle at about 1200 rpm I had wife spray the throttle shaft area with carb cleaner, rpm did increase abut 2-300. I even checked out the air/fuel screws, the timing, set the dist gap, changed the old fuel filter too. I have been doing the rust repair dance and just start it occasionally and let it warm up. Had been great till I changed out that too light return spring. Maybe that is why the previous owner had it there!!???
I found a 2 bbl Carter on the shelf that looks like a likely candidate. If not I will look for a local 4 bbl intake, prefer just an OEM heavy one! Cheap!!