Hyundai Repair: Engine misfire at low idle., obd ii code reader, hyundai elantra

Question
How do I check for codes and what is the codes list on a 1999 Hyundai-Elantra wagon-2.0-DOHC ENGINE?
Thank you for your quick response.
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-----Question-----
What can cause my '99' Elantra to idle rough then smooth out after a suggish start? 'Check Engine' light is also flashing.
-----Answer-----
If your car runs normally off idle, I'd suspect an intake manifold leak.

The check engine lamp is flashing because the engine control module (ECM) believes the misfire to be so severe that catalyst damage may occur.  If you read the trouble codes, it'll tell you which cylinder is misfiring.  You'll have a code P030x where x represents the misfiring cylinder.  (P0300 represents multiple misfires).

Answer
You'll need an OBD-II code reader to check the trouble codes.  It'll plug in to the Diagnostic Link Connector (DLC) under/behind the left side of the dash.  

The list of codes is too long for me to give here, but you should be able to find information at this link:
http://autorepair.about.com/od/obdcodedatabase/a/OBD_1996_year.htm