Hi,
After my Passat 1Z suddenly lost power at higher speeds and when driving uphill (entering a limp mode), I measured the boost pressure using VAG-COM, and it turned out that the boost pressure was far too high.
After receiving multiple hints here in the forum, I replaced the magnetic valve for boost pressure limitation, and lo and behold: everything is working fine again

.
(Title changed - I think the main idea should be recognizable from the title itself / Best regards, Ulf)