MPG not what it used to be, any ideas?
I have a 2003 Galant with the 4G64 4cyl. 186K miles. I know its probably getting tired with that mileage, but my fuel economy isn't what it used to be. I owned the car since 2005 when it had 37K miles on it, and up until about 150K I always got 390 to 400 miles on a tank (~29 mpg), for the last 30K miles, I've been averaging only about 300 to 330 miles per tank (21 mpg). Air filter is good, tranny was flushed at 150K, tires are good, timing belt and balance belt with all pulleys/bearings were changed at 160K. The only things I could think of are maybe plugs/wires, or maybe the timing isn't quite spot on. I don't have any error codes, but I might replace the 02 sensor just because its never been done. Any other ideas/suggestions?