Was going to ask - is the rack turning? Guess I've always done my adjustments with the engine off so never thought about it.
If you take a look at the diagram here =>
https://forums.pelicanparts.com/porsche-911-technical-forum/379815-mfi-diagram-routing-hoses.html
I think the main rack may not turn, but the low-speed / idle circuit does appear to be on the rotating portion of the internal assembly.