Sometimes the idle speed of engine is higher than expected, the main problem is that are described below
1. Check the fuel delivery, it is higher than standard
2. Check hose pipe leakage (for EFI engine) because If the hose pipe leakage or any leakage of air delivery into the manifold the mass air flow sensor can not recognized how much air is entered into engine except Idle control air valve. For that reason when air is inserted into engine the oxigen sensor response higher air and lower fuel that means lean fuel, Oxigen sensor informed to ECU unit to more fuel delivery as a result the idle engine speed is higher. So check hose pipe leakage.
3. If your problem is not solved, go to check idle air control valve, May be the idle air control valve is clogged, clean the idle air control valve softly.
I think your problem will be solved, if any question is arisen do not hesitate to inform me.