One problem related to emission control has been reported for the 1999 Hyundai Elantra. The most recently reported issues are listed below.
I was having problems with my car wanting to stall at take offs. When I took it in for servicing I was told I would need the mass air flow sensor fixed. I found that this was a recall issue campaign # 00v259 for all 1999 Elantras. My car however does not qualify for the quick fix unless I want to pay for it. This is already an issue with the 1999's apparently Hyundai needs to go back farther then the manufacture date of July 1998. Why mine does not fall under the "all 1999 Elantra" catagory is beyond me.