Info needed on IAVC

[SuperCow]

I bought an 190E 2.0 automatic from 1985 with some work. (euro model)
It has an IACV (Idle Air Control Valve) with 3 leads (A0001411725)


But its making an buzzing noise when the ignition is on.
When I look in the air tube of the IACV I see the turning valve closing for 5 seconds, then it pulsate open for a small moment and tries to close again and repeat the cycle.

It this normal? I did a little cleaning with breakcleaner, but didn't help.
When the engine is warm the idle is fine, but when cold its rough it doesn't get the higher idle. When I switch into drive the engine can stall.

I i think it has to do with the IACV. But don't know how it operates at normal

Any opinions?