Hyundai Repair: 2003 Hyundia Throttle Hesitation, hyundia, engine control module

Question
My daughter has a 2003 Hyundia Tiberon and when she first puts the vehicle in drive and presses on the gas pedel, the vehicle does not move, nor does the engine RPM rise.  When she lets off the gas pedel and then pushes it back down, the vehicle does begin to move forward and RPM rise.  The dealership has replaced the transmission and throttle sensor, but we still have this same issue.  Any help on this would be greatly appreciated.

Answer
It doesn't sound like a transmission issue because it accelerates on the second attempt.  It sounds rather conclusively to be an engine performace issue because the engine rpm does not increase when the throttle is depressed.

Additional information may help a little here.  First, what engine is in the Tiburon, the 2.0 four cylinder or the 2.7 V6?  Second, when, specifically, does the condition occur?  Is it only on the first start of the day or after the vehicle sits for a long time?  Does it occur only when starting from stops?

It's possible there are ECM (engine control module) reprograms available which would address this issue.  Regardless, if the shop can duplicate the condition and investigate while the condition is occurring, they should be able to find the problem and verify when they've repaired it.