VW FOX ignition system problems

Recently I have noticed some strange things happen with my 2005 Volkswagen Fox 1.4 petrol engine. On rainy days the engine always stalls when I stop, sometimes check engine light starts to blink, however it is rare. I always have to keep it above 2000 RPM otherwise the engine starts to sputter and stalls. But this happens only when it is humid, on sunny days there are no problems.

There seems to be no power loss when I speed it up above 2000 RPM.

When I bought the car, half year ago, the previous owner told me that he replaced the ignition module and spark wires so I just changed spark plugs.

I tried to investigate this by myself: I rechecked all plugs, there were no carbon build up or something out of ordinary, I checked each spark wire and they too seem to be good (no cracks, etc…). But I have noticed that there is spark coming from the connection between one spark wire and ignition module pin. First I thought that the wire boot might have microcracks, but then I switched the wires and again the spark was coming only from this one exact ignition module pin. I unscrewed the ignition module and inspected it but there were no cracks.
I sprayed dielectric spray on all connections but this didn’t help.

I am sorry if this is a dumb question, but could it be that the wire boots are too short for this ignition module pins? Or is it more likely that ignition module is the problem and I should replace it?

This is how the wires and ignition module look: