adjusting idle & carb balance : other mods ?

[roadrun_fr]

Idle is set around 1300 rpm.
The engine almost never stall.
The "rpm needle" isn't very stable : erratic between 1200/1400 rpm.
At neutral and snaping throttle quickly :
- The bike takes revs (5000 revs for example) and returns quickly to 2000 rpm then stay a little time at this revs and then return to idle
- at high temp, I often have a "pop" and engine does not take revs
- with pair system still working I can here exhaust popping while returning from high revs to idle

Have to setup pilot screws as well to richen/leanen a bit ? (pilot screws=mixture screws=idle screws ?)

This behaviour apart, the bike seems to run well.

I will do a carb balance this week end but what would you suggest to check/setup/mod at this time ?
Tuning pilot screws ? Disable Pair ? Shim needle ? Suppress manifold restrictors ?
In which order ?

I have a completely stock bike (airfilter/exhaust/jet settings/pair enabled)