I'd be concerned about that super-dark fluid. Last time I checked, chocolate/coffee is not one of the standard P/S fluid colors !!! Seriously, I've had cars where the inside of the P/S hoses were deteriorating, making the fluid dark and obviously contaminated. I've also had a pump seize up and cook the fluid. I'd flush that fluid out and replace -- it might quiet it down.
"Yes, that's right, its a Wagon..."