What rpm before it slowed? How far in was the idle screw? Still the #7 slide?
Ok, tried the 40/120. Turning the mixture screw out from closed, the idle slowed at 2 1/2 turns out.
Do this again but start with the mixture screw 4 turns out and idle screw mostly in. If the starting point is rich enough the idle will be at 1200 and speed up from there.