Wandering steering can be the radius are bushes, they should sit in the center of the axle mount if you can move them sideways with a bar they are shot.
Have you tried using the key fob next to the rear window to the right hand side of the tail gate as the ariel for the RF unit may be disconnected to stop battery drain.
Dont forget the dished washers on the pump mounts go a certain way they should dish )( that way not ().
and whey only need to be nipped up not screwed down tight
I have never heard a pssschhh on mine there is no dump valve to make that noise unless you have a split in the pipe work from turbo to inlet manifold you should not get a noise.