Hi Mattes,
I tried a product from Liqui Moly some time ago.
It should have cleaning, performance-enhancing, wear-reducing, and soot-reducing properties. Well, I didn't notice anything. I probably could have saved myself the trouble.
I might contact Bosch and inquire about possible solutions before spending hundreds of euros on a new pump. They also have those "miracle products."
But could you please search in the old threads here, as quite a bit has already been discussed there.
Greetings.
Thomas.