hello all. what makes a car start getting too hot when running, but not moving(idling)? when the car starts moving again the temp goes down to normal.

Check to see if the radiator fans are running with the A/C on when you are stopped.
If the fans are not running, it is normal for the temperature to swing somewhat warmer than when you are cruising down the road.
Then the temperature goes down when the fans come on.
I have posted in "General Windstar Information" about a problem with low speed fan operation, in case yours are not running with the A/C on test.

Also, low coolant will cause the temperature to swing hotter.

Of course, if the coolant is low, you will need to find out where it is going.
Slow leaks need to be investigated also, to make sure that the coolant is not leaking INTO the engine.

thank you wiswind. very helpful!!