Blocking vacuum pipes, not running in idle

[haaren]

I wanted to see how the engine would react if I block all vacuum pipes, blocked all pipes on plenum except for the brake servo off course. Only the hose of petrol flume filter I blocked, the other hoses are to the open air.
The engine will not run idle anymore, a bit strange so I checked all again and all is fine. Because it was a test I decided to take it for a short spin, with declaration it has some louder plops as usual but the most important thing it doesn't shunt with low refs / speed. When returning to my house it's trying to keep idle but the revs are between 400 en 1000rpm, it wants to stall but then quickly rev up. To be sure on my experience I mounted all pipes back as original, direct the engine runs normal idle again, take it for a spin and the shunting is back as well...
So experiment was a succes but now I want to know why it doesn't run idle when blanking off the vacuum pipes on plenum, does someone have more experience with this as of course I want to blank off all vacuum pipes to get rid of the shunting.
Thank you

[PabloGee]

Assuming you’ve found the “goddamn shunt is killing me” thread on here?

The shunt can be a few things, but the idea in that thread is that it’s to do with advance timing.

Might be time for a smoke test too, which could cause erratic idle.

[haaren]

There are no leaks, have done smoke test before also the idle with all hoses connected is normal.
I know the topic about advanced ignition, this I need to do as well but first I want to get rid of the "vacuum leaks" which are caused by all pipes on plenum.

[blaze_away]

Despite you believing you have no vacuum leaks the evidence you've presented says you do.

I'd suggest you repeat the excercise but blank off each vac hose 1 at a time till you can identify which hose is responsible.

I helped another owner recently and eventually after pumping in a lot of smoke we found the oil dip stick was sucking in air.

[haaren]

Now I get doubted.
When all is connected like original, the engine runs normal idle. When I blok all vacuum pipes of the plenum I get troubles with idle, connecting all hoses like original back again and engine runs idle. If I had a vacuum leak it should have issues when all is connected as well, at least this is what I presume.
Maybe I'm thinking in the wrong way or we talk not about the same, could you please share your thoughts why you think I have a vacuum issue?
I have a smoke machine so I can test it myself as a double check.
Thank you.