96 Cavalier Z24 with stalling problem?

I am curious... Im looking at a cavalier with a stalling problem the owner says that it does this at stops ocasionally. he says it starts right back up. He says the check engine light comes on with little or no warning that its gonna stall. now our van is a 1998 olds Silhouette and it had a bad fuel regulator that causes it to do this and it stalled at stops. is it a bad fuel regulator?

how expensive is it?

any help would REALLY be appreciated! thanks!