Clogged idle jet - may also be known as a slow run jet - or - I don't know which carb you have, there may be a "fuel-cut" or "anti-diesel" solenoid, which when de-energized blocks the feed between the idle jet and the mixture adjustment screw.
What are you referring to as the idle screw? There are (or should be) two adjustments, one for the idle mixture and a second for the idle speed.
The above is based on knowledge of the Aisin carburettors fitted to the 1.3 Suzuki Swift engines - whatever carb you have should be similar.