This is such a classic problem to all of us the 16V owners. Since the calibration procedure to this air mass sensor assembly is so intend and not so sucessfull.
I have the same problem with my car too and nothing seems to have fixed, so one day I adjusted the hex key about an eight of a revolution clockwise and the car seems to love it. It becomes very responsive thru out the whole RPM spectrum and no more getting stuck at high idle.
I have to admit that this is all luck.

Alex