my car jerks when I drive it on stop and go driving and on the freeway. The engine light comes on and it revs high when I drive it. When I'm at a stop and I step on the gas it doesn't move until the rpm is up around 4. But when I turn off the car and restart it, it works ok for a couple miles and then it does it again. I bought my car used so I don't have the 100,000 mile warranty. I have about 68000 miles on it and I took it in to hyundai and they said it was the input/ouput sensor and it costs $320 to fix. what do you guys think??