Truck Repair: idle overspeed error, mass airflow sensor, vacuum leaks

Question
1998 Ford Ranger 4 cyl 2.5L Had code read, pointed to idle overspeed. Replaced the IAC valve. It still idles overspeed until I come to a complete stop. It slows down but not as low as I think it should go. any suggestions? Thanks

Answer
Hello Bill,
Sorry this took so long. Personal emergency.
I would look for vacuum leaks, and then see if the egr transducer is plugged. It is a little thing about the size and shape of a domino, or a little larger, and has a vacuum hose to each end. They can get water deposits in them from condensation, and actuall plug up. It operates the EGR valve and could cause it to open incorrectly.
A dirty mass airflow sensor could also cause it.
See this link. http://www.fordscorpio.co.uk/cleanmaf.htm

Van