Slant six 1920 stall

Closest thread to my problem so thought Id tail on, sorry.
Ive been ironing out problems on the 63 dart 225. I installed a Super Six setup with a holley 2280 Id rebuilt a few years ago.
Got it where it is running very nicely but cant seem to get it to go to idle when stopped at stop signs or lights or stopping quickly even when warmed up well.
Ive raised idle up a half turn and now its up to 1500rpm or so and still happens, high enough that when I put it into D, it wants to take off.
Any thoughts on this? Check the solutions up above?
Thanks.