Coupe SE engine rev problem
 

I have a latest model Coupe/Tiburon SE 1.6 which has a rather annoying
problem with regard to the engine revs. When decelerating under engine
load (not braking) the car tugs incessantly and sometimes just carries
on going as if it is driving itself. When you stop at a junction the
engine revs rise on their own towards the red line. The only way to
stop it is to floor the throttle which brings it back to idle.
The car is fully serviced and has never produced a fault code when
interrogated by the dealer. I have asked two different Hyundai dealers
to look into the problem and neither seem interested once the readout
has shown no faults.
I asked an independant dealer to look at it and he admitted faults like
this do not show up on the engine management system and he thought the
problem probably lay within the engine management system itself, he
also thought the problem was dangerous!
I found on the net another post similar to this but on the previous
model, it had received no replies (posted in 2002) but it did say the
throttle sensor had been changed and had not cured the problem.
Does anyone have any ideas?