Hi Mvdb I have a Tucson diesel and I would suggest that you have a look at the injectors to ensure they are not all clogged up-
Then while your at it change the oil type to a part or full synthetic oil as it doesn't breakdown as much as a mineral oil.
Now as its had a heavy life is it perhaps a good idea to change all the belts so that these don't cause you a problem sooner rather than later and lastly come talk to other Terrican owners at
http://www.hyundaiownersclub.co.uk/index.php in GB as most of the members there are a helpful crowd even though you may be 000's of miles away.
This site is also extremely good although as in most places you have to wait till someone logs in to get ur answers.
I'm happy to recieve Pm's at almost any time and will try to find out info if I don't know (I am not a tech just an old git who reads alot)
I'm currently researching a product for all diesal engines so stay looking in .
Cheers for now
Itza :beer: