Varadero with unstable idle and possible loss of vacuum

[Mianfrar]

I tell you the problem
I bought a 2007 varadero 125 carburettor that had been stopped for 4-5 years, it wouldn't start and I did the following:

change oil
Disassemble and clean carburettors thoroughly
change spark plugs
Use carburetor cleaning products for both the more mechanical cleaning and mixing with the fuel.

After this I was able to start it but not without problems. The idle is unstable, if I accelerate to the limit and let go the revolutions drop quickly to 4000rpm and from there they go slowly, if I lower the idle a lot (1200rpm) they drop faster but then it usually turns off because it is close to 1000rpm, if I leave it at 1500rmp sometimes it revs on its own and you always see how the rev needle goes up and down slightly. For it to go moderately well I have to turn the pilot screws 2 turns when the manual says 3/4 but it continues to give similar symptoms to the previous ones although less.

I got one of those cheap vacuum gauges and I see that with 3/4 of a turn of the pilot screw it marks 50mm and it reaches 100mm with 2 turns, from what I see in the manual it should be at 280mm. I just did a test disconnecting the inlet from the air filter of the pair valve and at idle it sucks the same as at 12,000rpm, it only lets it suck for a moment (1-2sec) when I release the accelerator and the revolutions drop. I have thoroughly disassembled and reassembled the carburetor in case it had an air inlet and loss of vacuum but I didn't find anything, I sprayed with oil to see if I could locate something but nothing.

Could the fault be due to a leak? Can this loss occur for another reason? possible fault in the starter cable?