Power Steering and possible Thermostat probs

[Shift__BODOM]

1993 240sx FB1996 240sx KA24DE motor

hey everyone, ive been having a problem with my power steering for a while now. for a short time my power steering pump would whine, esp. when i turned the wheel, and i got very poor feedback at best from the wheel. i have since dropped in a new engine, and the power steering pump doesnt even seem to be working at all. there is no whine, but there is also no power assist. after a few days, however, it seems thta the power steering has returned slightly. although it isnt enough to convince me that my power steering pump is "magically" working again. anyone know what's wrong? i have yet to talk to a mechanic about this since they are probably going to have me get a new P/S pump...which is probably what i need...anyway, i just need a little bit of insight here. are there any known problems with this model/year's power steering? gaskets messing up, lines getting clogged etc.? side note, i ran lucas stop leak for power steering systems for a while, and the problem just continued to get worse. right now, the P/S fluid level is ideal with no visible leaks.

now, on to another problem. while driving the other day, i noticed something very strange happening to my water temp gauge. upon warming up, the needle sits strong in the middle of the range, indicating that the car is at normal operating temperature, however, after less than 5 minutes of normal operation (we're talking driving very slow, shifting at less than 3k RPM) the needle quickly, but gently, falls down to almost completely cold. it usually sits right between the thick bottom line and the first thin line. my thought is that it is a thermostat problem, but i really dont know where to start looking. ive checked for codes, and none are being sent...which kinda bugs me...

anyone know whats going on with my car? any help is greatly appreciated.

[FliMSiCaL]

about the power steering, i don't know, i destroyed my shaft seal a few years ago doin 100 down the interstate late for work, so i just took it off. there is a huge known temp gauge short problem in these cars, and i've spent quite a bit of time looking for it. i've come to the conclusion that its shorted in the gauge pod...i just ignore mine for now, as my engine has other ways it lets me know that i'm running too hot.

[Dattebayo]

There is a switch that can go bad on the PS line. It could explain whats going on if you dont hear any whine. It is listed as power steering switch.this is what it looks like: