How do I tell what the codes PO171 and PO174 mean on my 2003 Windstar?

What is your question?

I was wondering if my car does not have a visible vacuum leak, if there is a way to know based on symptoms where to go next with a PO171 and PO174 code? I know a problem with the intake manifold gasket is common, but it seems so is a mass flow air sensor that may need cleaning. Or perhaps an O2 sensor issue. The car starts up fine, seems to accelerate okay, but when stopped at a light it kind of bucks back and forth a little and one time it stalled. Any suggestions on what to try first would be most appreciated!

What makes this problem better or worse?

Being stopped at a light

How long has your 2003 Ford Windstar had this problem?

A few days but just bought the car