Running rich doesnt have anything to do with your WGDC, play with your OL targets. At idle you dont need a lot of WGDC as you arent making any boost. From 50% throttle I have mine set to ~90% from ~1500-3 or 3500 RPM. What you can do is lower the table say 10% and see if your still hitting target boost. If not raise a couple of PSI at a time and re-check. For the flutter you most likely need to lower the WGDC in that RPM range.
edit: Got home from school. The last 2 columns (87.5 and 100% throttle) I have set to 80% wgdc from 2000-4000 rpm's, then 67 down to 57.