Also: You can waste a lot of time and money chasing potential causes of various symptoms.
Let's start with specifics: Does the check engine light remain on while the van is running? If so, get it scanned (note that many auto parts chains - including AutoZone - will often scan for free) and get a list of specific codes (i.e., not just vague descriptions like "rich fuel").
Post the codes here, and we can help you diagnose from there.