acceleration problem

This may need to be closely tested at a delership, but more than likely there sounds like there is an issue with your Throttle Posiition Sensor. If there is an internal fault in the sensor it can cause a difference in the correlation between how much you are accelerating and how much the throttle actually opens. For instance, you could have your foot 70% on the accelerator but due to a fault in the TPS it may be opening and shutting the car like crazy causing a jerking and inefficient acceleration. However, the TPS works within a certain set of parameters, (usually 0-5 volts), so as long as it is operating within these parameters, the computer has no way of telling that there is a problem with this component. So basically, it could be opening and shutting or barely evenoving but as long as it operateswithin 0-5 volts the computer will see nothing wrong with it so this is why the previous technicians have found nothing when they have scanned it for error codes. In my experience, it would be best to first clean out your throttle body with a can of throttle body cleaner and a rag, then, if the problem still occurs, take it to a hyundai dealer and get the sensor tested