Rough engine run on low rev

[BellaMacchina]

Hello,

I have a problem on my 81 fuel injected CS0:

With cold engine, the engine runs well and smooth.
As far as it reaches some temperature, the engine runs somehow rough in idle and in low revs. If feels like it would miss some ignition strokes from time to time, and you can hear it popping on the exhaust.

As far as there is a higher rev, the problem disappears. I can drive without problems in higher revs or with more acceleration. But if the gas position is low in low revs, it starts to behave shaky.

The pickup and the control module of the ignition was alread renewed.
Also the air flow meter unit was changed as a test.

I would be happy to get some good tips on how to start finding the problem.

Best regards and thanks in advance
Marcus