[wiswind]

Your profile says you have a 2000 windstar, which I am not familiar with...as I have a '96.
The made major changes in '99.

I would find it hard to believe that your water pump would cause enough of a drag to load down the engine.

You could try loosening the serpentine belt and turning the water pump pulley by hand....and see if it is hard to turn.

I would give the idler pulley are real hard checking out.
On my '96, it is right next to the water pump......etc.
They are known to fail.

Also, check to see if the tensioner is holding the serpentine belt tight.....and also check to see that there is not any oil / coolant, etc on the belt and pulleys that could be causing it to slip.

The windstar is also known for cooking the power steering fluid.....and the worn out fluid will make the power steering noisy.