After 2 days of action of the wd40 oil, I unscrewed the spark plugs without any problems. They were all burnt. I replaced them with some new NGK ones.Then I packed everything back up. The car is running fine so far, I'm curious if the sudden loss of power still occurs. Anyway the intake/spark plug part is solved. I'll come back with news if there will be. The good ones!

Can anyone confirm the start of VIN numbers that indicate no swirl flaps?

I got this off LRCAT - seems to indicate no swirl flaps from VIN BH000001.
Can someone else confirm this info please.

My car is MY11 and the local parts manager only lists one manifold LR019987

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You can tell simply by looking at the inlet manifold. If it has the vacuum actuator on the left of the manifold, it has swirl flaps. If the manifold has the mounting position without the vacuum actuator fitted, then no swirl flaps are in there. 2009 Rimini Red SE TD4. Soon to be sold.
Hyundai Ionic 5 Ultimate on order.
Gone. 2006 Tonga Green i6 HSE.

That's correct. No swirl flaps to worry about.  2009 Rimini Red SE TD4. Soon to be sold.
Hyundai Ionic 5 Ultimate on order.
Gone. 2006 Tonga Green i6 HSE.

As promised I'll be back with feedback. The elimination of swirl flaps led to an increase in extra-urban consumption by about 1 liter/100km. Interestingly, this increase occurred before the intake manifold was removed most likely when the throttle arm broke and the throttles were spinning freely in the intake air stream. I can conclude that I was very lucky to have removed the manifold and removed the valvetrain before the broken valve stem wear was sucked into that cylinder and destroyed it. Now I need a resoft to get the diesel consumption back to normal. What do you think about chip boxes, are they a solution or just a scam? https://www.ebay.co.uk/urw/SAAB-Digital-Di...&pgn=2

If anything on the air path has been replaced, then an air path calibration is needed to optimise the system.

Anything that plugs into the OBD2 port that claims to improve economy is a scam. 2009 Rimini Red SE TD4. Soon to be sold.
Hyundai Ionic 5 Ultimate on order.
Gone. 2006 Tonga Green i6 HSE.