Thanks Maximo for that excellent write up.
I've been chasing a idle down problem on my new Picco .28 Team Turbo. I have sealed up everything in sight with silicone and that helped but I still have a problem with then engine idling down nicely when it's hot. It's not consistent but the things you've mentioned make some sense. I have tuned it when hot but nothing has completely solved the problem.
I did some leak testing on the carb prior to mounting it and did find the leaking area you pointed out and that was at room temp. I did seal the carb to the crankcase which I figured might solve that problem.
I think I need to get some of that Permatex thread sealant next. I used some green slime on the threads and O-rings.
For reference I'm running the Picco hot plug and O'Donnells 20% race blend fuel.
DM1-S Tekin 2650Kv
MTX-3 MR .12
TA05 IFS-R Tekin 17.5
TA03R Cirtix 17.5 club spec
F109 Tekin 21.5