holley 750 dp...mystery vacuum leak

had a few stalling episodes with sb 416, never had problem before. new filter/mechanical pump nearly new,presssure good at 6psi. stalled when coming to a stop, raised float level a bit to bottom of sight level hole. stalled again few days later.
after attempting to adjust idle mixture screws i find i can run them in and no stall or little effect on idle.
after spraying carb cleaner while idleing at every gasket/vac line etc i cannot find a vac leak. is there a possible internal carb problem that would effect the idle mix screws???

If your throttle blades are open too far the idle mixture screws will have little if any effect.

Quote:

---

had a few stalling episodes with sb 416,

---

eng off, remove the idle mixture screws and shoot a 2 second blast of starting fluid into each side port using the thin red straw then replace the screws. This works if dirt in the idle circuit is making it stall