I have this sportage that my oldest son drove the wheels off. Now i am stuck repairing it and making it a daily driver to and from work.
I noticed this evening coming home from work, that a vibration and noise was coming from under the car.
I got home and crawled under the car to "look around"
I noticed the driveshaft is a two piece unit with a bearing or something in the middle. After messing around with it for a few minutes, i noticed ( or at least feel ) that this to really loose fitting.
I did notice on the way home, that once i got up to speed the vibration would settle down, and the noise went away, which i why i am assuming this could be the issue. As the driveshaft increases in speed, the unit "might" center itself causing less vibration and noise.
Does anyone know what this unit might be called, and if in fact it should be a tighter fit that it seems to have ??
Hope someone out in the net world might know something that could help me...

Is this a 2wheel drive? the 4x4 has one piece shaft to the rear....or..well, I mean it is not supported by an extra bearing in the middle.....is this rather the telescopic part of the shaft you are talking about ? It might be worn out. It has a greaser in or near the middle .
http://www.avigex.ca/kia/drivingshaft.gif