One problem related to gas recirculation valve (egr valve) has been reported for the 1998 Plymouth Grand Voyager. The most recently reported issues are listed below.
Driving to store. Weather was clear ~ 85 degrees f, road was clear, no rain, time approximately 10pm. While driving, I moved into the center lane (major road, three lanes both ways) for a turn to the store, during my turn to the left, I noticed that my power steering was not functioning and very hard to control/steer the vehicle. After struggling to straighten out my van (1998 Plymouth, Grand Voyager se) I noticed that my engine temperature had gone off scale / over heating. At this point I stopped the van in the middle of traffic.