Under normal circumstances the engine idling speed should not affect the steering effort.
When engine is started from cold, the idling speed would be higher and pump is putting more pressure and when it warms up, the idling speed would drop reducing the pressure. This symptom indicates a fault with the pump and I would suggest getting back to the people who did the job and getting them to resolve it for you under warranty.
Wednesday, January 23rd, 2013 AT 6:10 PM