Check that the throttle position sensor is operating correctly, and no debris has gotten on the contact. This would not necessarily generate a code, but would give you a rough idle. Clean off the contact on the oxygen sensor also. If you live in the North East, the nice people who rip us off for fuel, had added Ethenol to the fuel. Try running a good fuel injector cleaner with Methanol in it, or have a mechanic do an isolated fuel injector cleaning. My mechanic just disconnected the fuel pump fuse, and put a small pressurized tank full of clean gas and methanol and injector cleaner, through the injectors. Made a world of diffrence. My misfire was from bad gas that showed up all over the New York area one week. The poor quality of the fuel causes the computer to try to corrct the problem, and it does this by retarding the timing, i.e., rough idle, and runs hotter.