Engine Stumbles and Revs Stick

[senoel]

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2002 Hyundai Accent 1.6 48,000.
No mods to engine.
Services made: Ign wires, Plugs, Fuel injectors cleaned, Air Filter replaced, Oil & filter changed, Coolant

Hose is attached to throttle body's underside. Do you think there is a leak in this hose? I've had a problem with engine faintly stumbling at highway speeds (60-75mph) and Revs sticking after stepping on clutch to begin slowing down. The needle for Revs drops slowly after hitting clutch to switch gears, slow down, or to come to a stop. Sometimes it will decrease slower than other times. It used to be worse when I would step down on clutch to slow down and the Revs would climb to 4000+. I have lowered the idle screw just enough where it’s between were it wont climb anymore and gas pedals isn't to hard, but Rev needle still sticks and drops Revs slowly.