I am in need of one of these but want to know what its for: EGR Vacuum Solenoid, located on Passenger firewall where the MAP sensor is,
page 218 figure 2 1989 EVTSM
...that valve dumps a small amount of burned exhaust gases into the intake on deceleration to help dilute unburned and/or partially burned fuel/air in an effort to reduce emissions out the exhaust into the atmosphere. The solenoid is the vacuum operated device that opens/closes that valve.