If there is a kink in the return line, the fuel pressure regulator may not be able to releave enough fuel pressure from the system to the tank. As a result, you may be getting too much fuel to the cylenders. As far as the O2 sensor, it should be replaced. It too could cause a rough idle problem.
Now the cylender that wasn't running. Did you remove the plug? There is a good chance it is no good if you were driving it with it that way. You may want to replace them all if it has been a long time since the last tune up.
Let me know if you need instructions for anything I mentioned.
Wednesday, February 17th, 2010 AT 10:10 AM