This car is a '98?
There should be some provision in the electronic tuning to allow the idle to "hang" a bit longer during chop throttle events. A vacuum operated bipass valve most likely is used for that function. If so it needs to see the signal a little differently or for a bit longer.
RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8