Search the X-type section under vacuum leak or 0171 and 0174 codes or lean codes or PCV hose or IMT valves or brake boost hose. Those are your 3 likely culprits. Change them all if they haven't been done. On an '03 if your PVC hose isn't the new reinforced one, you will find a split on the underside. If your brake boost hose has the white check valve, it is the original and prone to deterioration. Undo an IMT valve and if the gasket isn't green, you'll need to get them. 99% it will be one or all of the three.

 

On General Tech Help, we recently covered this very code ,you can see the topic on the 1st page
Thanks mohrd for his reply as well