Throttle issue

[Eldon]

Just bought a 2007 s4r monster. The issue with the throttle is when I close the throttle the rpms don't drop to idle speed right away it stays at 1500-1600 rpms for a second or two. The linkage is fully closing grip is not getting stuck. The bike has a microtec ecu.
If I let the clutch out a little in gear it will drop to idle speed then seems fine.
Thanks.