Vibrations - Problem with injection timing?

Hello, I'm experiencing the following symptoms:

Severe engine vibrations in all gears, both while driving and at a standstill, with and without the clutch engaged. The vibrations are most noticeable at low RPMs and then again between 2000 and 3000 RPM. It's significantly better, or at least normal.
The vibrations travel all the way to the pedals and the gear lever.
The ZMS (presumably referring to a specific component) was replaced along with the clutch, but there was no improvement.
I just bought a VAGCOM device and read the error codes.
"The following error occurred:"

17656 Injection Start Regulation: Control deviation P1248 - 35 - 00.

Who knows what that (exactly) means. And what should I do now?

Thank you, best regards, Bernd.

Search function with the word '17656'