Recently purchased my 2000 Mercury Sable GS station wagon with a 3.0L vulcan engine. Have replaced the air filter, DPFE sensor. Tomorrow will replace the plugs and PCV valve. At present am not showing a check engine light and my scanner is showing no codes. Vehicle has 181,000.00 on it but was told mostly hwy. miles. Am trying to figure out why I am presently getting only 19MPG this is really low. Engine seems to be running ok but the low fuel economy bothers me. Any ideas?? Will check this forum in the morning. Bob S.