2002 MPV ES with 118,550 miles threw a couple codes. A 171 and 174 I believe. NO ISSUES other than the codes. Ran Great. A bottle of good cleaner and a new air filter and the codes didn't come back at that time. So, the van took a trip to Nashville, to northern Indiana and back to Nashville and then home with no issues and no check engine light. 3 days after the return home, check engine and it started running bad. 6 codes this time.
Took 10 minutes and a can of carb. cleaner to find the vacuum leak. The hose is on the back of the intake. The picture of the engine has an arrow pointing to the elbow that developed a hole after 22 years of use. The part is a Mazda part and a Ford part. So, if you have access to a Ford dealer, here are the Mazda and the Ford Numbers. You get the elbow and the hose. I did. $85 bucks.

 

Cool! Problem solved then?