Ok, have you tried this.
1)You need more air "leaked" around the AFM sensor. (There is a stock port in the lower passage, with a bolt in there. That bolt is tuned/turned to give you FC at about 12 to 13 psi of boost based on air flow through the stock AFM.)
By opening up that port, you "leak" or bypass more air around the Karmann wave signal meter, and that allows you to "lean" out the engine some while also allowing more boost pressure/air flow before your computer does FC.
It is simple.
Remove the AFM.
Remove the sensor. (Three screws.) Do not touch the sensor tube, and lay it off in a safe place where it will not get damaged.)
Now, drill out the plug cap over the screw in the small air passage.
Do not damage the honeycomb screen in any way. Be careful with this, it's expensive to replace it.
Ok, when you have a hole in the plug, often you can pry it off/out with a small screwdriver. If not, just drill it out completely.
Now, with a larger common screw driver, back out the stock air screw plug till you can not see it blocking the lower air port.
Put back in the sensor, and see if your FC is now higher.
If you want more, you can put a small K&N style filter on a un-used port of the accordian hose. (If you have an un-used one.) That will leak even more air, and raise FC even higher.
If your car is running super rich, this might cure it. I'd try the screw mod first, then do the filter if you think you are still rich, but testing with a wideband is much safer when you start doing mods like this.
Good luck.