injection pump
 

will a ds4 pump from a 95 work in a 98?

According to autozone's website the replacement pump is the same on both of them. I think only the 92-93 were different since they had mechanical pumps.

94 may have an orphan 5068 IP,it is the only electronic IP that is not interchangeable because of ECM programming.

In order to use another model IP on a 94 that came with a 5068,the chip must be reprogrammed.
Otherwise all the other electronic IP's are interchangeable.