Does my 2001 Windstar have both upstream and downstream o2 sensors?

You can go to the auto parts store websites and look up your vehicle to see how many o2 sensors you have. If you call the dealer service counter or muffler shops, they will usually give that info. too.

Thanks, appreciate the help.

Also, your vehicle has an egr vacuum solenoid on the engine. Should be on passenger side back of engine. It is designed to sense the amount of moisture in the exhaust, if my memory serves me right.After awhile they stick and fail to measure properly. They are known to be a common issue .