Originally Posted by Brian Carlton

13" a bit high for idle.

I'd make a small adjustment to the vacuum amplifier (blue flying saucer). Remove it and you'll find a black plastic cap on the bottom. Remove the cap and you'll find a plastic hex screw..........4mm IIRC. Turn the plastic hex screw clockwise by two turns and reinstall the amplifier in the vehicle.

Reconnect it and take it for a drive. See if the flare is gone.