Haven't you ask them what they will do in 3K, I mean breakdown of items and see if it really make sense or it's just a milking cow usual behavior. For reducing HC, for sure get the air filter changed and also see some good mechanic to diagnose the Vacuum leak or additional air going from some seals. Idle speed control sensor should not be changed unless car showing some error code for that specific item. For less driven car, I would have suggested that to put the fuel treatment bottle (STP or cyclo) from eppco emarat for 50 bucks in quarter tank and drive at 140 to get rid of all carbon deposit before you hit Tasjeel.