idle problems on 106 1.4XT

[pug3]

Can anybody help me?

My wife has a 106XT and it keeps on having idling problems, i have looked at the carb and there is a little servo or something attached to the bottom of the carb this is going mad in and out all the time causing the car to idle fast then slow and sometimes even cutting out, i have cleaned the connection with no resolve any other idea's please.

thanks