I am the owner of a 2001 Ford Windstar LX. The check engine light came on at about 78,000 miles. I checked the OBD and retrieved codes P0171 and P0174. I thoroughly cleaned the throttle body and MAF sensor. I cleared the codes. It took about one month, and the codes are back. I have read it could be from the intake manifold runner control, or TSB 3-16-1. Is there any way to narrow it down? My extended warrany expired at 75,000 miles. I never had a problem with the check engine light until now.