I just recently purchased a beautiful 2004 ford taurus se with 3.0L engine. It is in need of some serious TLC. It has 155,000 miles on it, and the check engine light is on constantly. I had a misfire in a couple of cylinders and also EGR codes came up. My husband replaced the spark plugs, which were completely burned up, and replaced the air filter and the spark plug wires. He also installed a new EGR valve. As soon as he was done with the tune up, it was idling roughly, so he adjusted the hard stop screw for the throttle. This did not help, so he adjusted it some more. Still did not help. Finally, he realized one of the spark plug wires was not fully seated, and as soon as he re-seated the spark plug wire, the engine was idling real high sounding. He turned the screw down, and now the car is idling at about 850 rpms with the car in park. It runs like a dream going down the interstate and the gas mileage jumped up from 16 mpg to 27 mpg. However, after having the check engine light reset, it has now come back on. The new code coming up says it has detected a rich or lean Air/Fuel ratio condition on engine bank one and two. We are sure this has to do with him turning the throttle screw. Can you please tell me what is the factory recommended rpms for this year taurus to idle at? Or how can we set this screw back to its factory setting?