Throttle flap actuator motor

[Davie83]

Hello, I've had a problem with my car (st170) for a while. The engine management light has been on. The only real issue when I drive it, is there's a slight stutter when I accelerate beyond 4K rpm.... I took it to the mechanics and they couldn't pin point exactly what was wrong with it, although it has to do with the throttle flap not opening properly, they had a look at the wire that operates it and there wasn't a problem there. Then they told me they spoke to someone who specialises in what they had found out and said I need a new "throttle flap actuator motor" They've told me it's an expensive part. So I've been trying to find the part online, either reconditioned or from a breakers, but I'm finding it difficult to even get a picture of what I'm looking for.... has anyone had a similar problem? or does anyone know what I'm looking for and how to get it?