The steering on my Ex isn't working like it should. At times it feels loose when cruising then feels tight when straightening back out after a turn... the wander is really bad...

My PS fluid is also turning into a muddy brown goo every 5k... I changed the PS pump this summer with a supposedly good used one...

What should I be looking at/checking for?

 

Might be time to look into a Red Head.

Until then, have you tried adjusting the steering gear?

https://www.ford-trucks.com/forums/1...g-box-buy.html

When you replaced the pump, were you able to flush out the old fluid?

 

Yea I got all the old fluid out and replaced it with new ATF

 

Here's the steering adjustment thread - takes a while to get through, but worth a try.

https://www.ford-trucks.com/forums/5...-steering.html

 

Yup, if your fluid is turning brown after flushes I bet the box is having problems. I'll also agree with changing the steering box.