Carb blues, please help asap!

[Cw72gmc]

So i've been having carb issues, after tuning up my truck is performing better but still having stall/hesitation/low idle issues. 72 gmc original 350 with a quadrajet carb.

Anything below 1500 is hesitant and bogs. Anything from 1200-4000 rpm feels normal does not miss or hesitate.

Truck used to idle high some days low others, now warm I am idling very rough at 400-500 rpm. firing does not smooth out until I put the pedal down quarter way. If i put the truck in gear and i'm less than 1500 it just bogs violently . it is a manual tranny.

I dont know where to start. all ignition stuff has been changed in the last two weeks, problem has gotten worse in the last two days. Also i noticed a spring from the passenger side carb sitting on the manifold, not sure where it goes?