I have a 2004 Taurus SE. 155,000 miles. I was getting numerous codes. I replaced spark plugs, wires and air filter, that got rid of the misfire codes. (Plugs were fried). I replaced the EGR valve and that got rid of the EGR codes. My husband thought he was doing good and he adjusted the hard stop screw on the throttle. Car ran like crap and kicked out these new codes Po171 and P0174. He re-adjusted the hard stop screw and now the car idles in park at 950 rpms, and when it is put into drive with the A/C blowing it is idling at around 700-725 rpms. It is driving and idling really well. So we let the car set overnight to have a cold engine, disconnected the battery and reconnected and followed the steps to allow the car to re-learn its idle and trim. Everything was great. SES lite was off, car was purring like a kitten. Gas mileage is up to 27.2 mpg. Drove it about 80 miles and the SES light has come back on. Kicking out the same codes P0171 and Po174. Anyone got any suggestions what to do to fix this issue?