EGR & MAP Sensor Cleaning
 

I have been reading threads about cleaning the EGR system and the MAP sensor. I have never done this. Does it improve fuel efficiency and about how much? What all parts need to be cleaned and what do you use to clean them? Do the parts need to be removed from the car in order to clean them effectively? How often should it be done? Is it worth the time spent doing it?

Which car? I'm sure your excort is mass air flow... at least the 97 one. If you do clean the mass air flow use an electrical contact cleaner and DO NOT touch the exposed wires on it.

I was more concerned about the '88 with 475,000 miles it is probably due a cleaning.

Make sure you buy throttle body cleaner. Old fashioned carb cleaner will remove the special coatings on the inside surface of those sensors.

Or MAF cleaner.