Do some searching here re. AFMs and you’ll find a thread that chronicles my year long fight with engine management problems. It turned out the problem was that my AFM spring had been loosened, a ghetto solution that is supposed to allow more air flow. An AFM that is working precisely as Bosch intended is a treasure.
When I was young and didn’t know any better I let a couple people dick with my AFM spring. That led to a tough year where I did all sorts of wild shit trying to fix possible causes of my engine generally running like crap at WOT. If you have an AFM that you know for absolute fact has never been screwed with, guard it like a virgin daughter. Most engine management “performance tricks” are bad ideas because we don’t know what we don’t know.