stalling with AC on, coming off of idle

My '74 Valiant loves to stall when I have the AC on when I'm stopped at a red light or stop sign, and then I ease off the brake and onto the throttle. I've bumped up the idle quite a bit, but it still does this. I'm thinking my v-style compressor may be overcharged with refrigerant. Any other suggestions? Without the AC on, this never happens. Maybe an adjustment to the accelerator pump? Holley 1945, if that matters. Mixture too lean/rich?