Had the same problem, I replaced the spark wires and the rotation switch (it can be found on the top of the machine straight in the middle and nearest to the window with a single wire in it, unplug it put the car into neutral and see if the there are absolutely no changes in the cars reaction (when you step on the gas if it shows normally the bar for the rotations rising like it always does) then this switch is dead, and when this switch is dead the cars computer doesnt know how many rotations there actually are and my car even died on the freeway @ 150km/h. Happens with Prides all the time) and it works fine now.
My electrician also told me that my computer was fine and everything (come to think of it the computer is fine and there is no way to determine if a switch is screwing up) but sometimes you have to figure out these things out for yourself. So that you don't have any problems locating the switch here's a picture of my old one that I took out so you can find it easily (had to scan it since my camera is out of commission);
Front:

Back:
This is the only thing that can be wrong in this case and I'm 100% sure that this switch is the problem.
Replacing the switch is so simple, unplug the wire unscrew two screws, put the new one one and screw it up, just go to your Kia supplyer and tell him the nubner on your switch (that's why I left the pictures so huge that you can see where the number is written).
I live in Europe and we only have 1.4 Mazda engines in Prides so the location of the switch may vary, but I think they should be about the same.
Cheers,
shorto