Slow engine rpm drop after rew

[Ram Air IV]

Hi, I have 2002 LQ9 (6.0L) in my Firebird -68. When I rew my engine the rpm drops fast from lets say 4000 down to 1500 but then there is a delay of 3-5 sek from 1500 to idle (600 rpm). This is little bit anoying. Is there some parameters that can be tweeked so the engine rpm drops down to idle direct? The engine is stock (drive by wire) except long tube headers, dual 2,5" exhaust system, K&N air filter.
/ Magnus

[pullincrazy88]

Don't quote me on this but I believe you can play with the throttle cracker or throttle flower to get the rpms to ramp down faster or slower.