1992 Toyota 4Runner Engine run rough

Engine Performance problem
1992 Toyota 4Runner 6 cyl Two Wheel Drive Automatic 3000rb miles

My engine runs rough in the mornings especially when the weather is cold. When the idle speed adjusting screw is move roughness starts and a rich gas smell is emitted from the exhaust runs smooth later in the day when engine warms up. Also a sound of air escaping come from the engine what do you think? Broke owner