diesel rough idle
 

hello everyone. i am looking at buying a 99 beetle with a diesel. it runs good at speed but when at idle it seems to be rough. I didnt see any smoke coming from the tailpipe. I also looked at the engine while it was running and it is shaking quite a bit. when sitting at a light with my foot on the brake it seems to surge a little also. It is an automatic tranny.
I am not familiar with these cars and was wondering is this normal or not?

Any help would be greatly appreciated.

If its not normal, what could be some possible problems?
im just worried that i may be buying someones elses problems.
Oh it has 130,000 miles on it
if you need more info just ask and i will do the best i can to answer your questions.
Thank you