2004 elantra engine stalls/jerking

Hi,
I have an auto, regular oil change, 80k, mostly highway miles, 04 elantra.  Recently, the engine stalls/jerks when it is crossing only between 20-30 mph.  After 30 mph, there is no such symptoms.
Local mechanic says it could be spark plug and wires problem.
Is there anything wrong that I need to check on my car such as timing belt, sensors etc?
 
Thanks in advance for you tips and suggestions

First, I doubt there would be a timing belt problem BUT if it has never been replaced, you are 20K miles over due.  Get it changed quick.
 
As far as the hesitation goes, I'd check the throttle position sensor, the plugs and wires.  Are there any codes in the computer?

Thank you, NovaResource.  I am the orginal owner and hence the warranty says it is covered until 100K.  Regarding computer codes, where do I find them?. Is it something that I should be able to find out?

Yes, the engine is covered for 100k miles but Hyundai requires the timing belt be replaced at 60K miles as part of the owner required maintenance.  Since you are past 60K miles and did not change the belt, if it breaks, Hyundai will NOT replace your engine under warranty because you failed to do the required maintenance.

quote:

Regarding computer codes, where do I find them?. Is it something that I should be able to find out?

To answer your questions, error codes are kept in the car's computer memory and can only be read using a OBDC-II code scanner.  Relatively good ones can be purchased for ~$100, but many parts stores will extract codes for customers or loan scanners to the customer for their use.  Your stalling/jerking problem could be caused by a number of things, but I'm guessing the transmission has a problem shifting from 2nd to 3rd gear.  Yes, the transmission has sensors and can generate error codes that the scanner will pick up as well.  Once you know the code or codes, you can look up what they mean at the Hyundai service site:

http://www.hmaservice.com/