My wife has a 2001 Santa Fe, 2.7L, 4WD, 6 cylinder, Check engine light came on, plugged the code reader in and it said bad crankshaft positioning sensor. Went and bought a new sensor and installed it. In the process of installing, it required removing the fan, for an easier time replacing the sensor. I then put everything back together, though I forgot to plug the fan back in. I drove the car a couple of miles, and it was perfect, fixing the symptons of the faulty sensor. After 2 miles of driving, the car overheated and started running horribly. I couldn't get the rpm's past 1200. It will stall out, and could not go faster than 8 miles an hour. Limped it home, and I figured I did something to the new sensor, and replaced it a second time. It did not fix the problem, resulting in the Check engine light back on, saying that there was a misfire on cylinder 4. By letting it overheat, did I casue a bigger problem by getting the misfire? Is it related to the overheating, or is it by coincidence, that a new problem arose at the same time the sensor went out. When checked the misfire, took the spark plug out and there was oil in the spark plug well. I bought new plugs and wires, and still have the misfire and still getting oil in the spark plug well. After looking into this issue and doing research, I am hoping by replacing the valve cover gasket, would make a tighter seal around the plug, preventing oil from entering the well. When I replace it, and there is still oil in the plug well, what other possibilities could be going wrong? The only code coming up is P0304, misfire cyl. 4. No other codes are showing up. IF anyone has any ideas that I may be overlooking, by all means please let me know!