Saturn stalls/revs

Working on a 98 saturn sl1. It has intermitten issue with stalling out and reving up. It will sometimes stall out when put into gear or stoping at a light. Other times it will rev way up, ab out 3500-4000 rpm and eventually come back down. Thought the stalling may be vacum leak related but can not locate an external vacum leak. Now it has started reving up really high from time to time. Could this be fuel pressure regulator issue? No codes have come up.