Noises
 

im getting noises from the rear and then a water sloshing type sound when i turn it over. I cant figure out what the water sound is. I checked the oil, power steering and coolant reservoir and they are all full. does anyone know what that might be. also, when i go down the road theres a squeaking in the rear, im thinking its a suspension problem but i dont know. I tested the suspension by pushing down on the car and it rocks like a boat on the water. I just got the supra (88 MKIII n/a) a week ago, so i dont know alot about the suspension and everything so anyones input would be appreciated.

do a thread search for 'waterfall' behind the dash. Its air in the heater core.
The back hatch is a 'known' squeek problem. Silicone spray at the rubbber contact points can help.

Shocks may be worn out. There are several threads on replacing them with various types, depending on what you are gonna do with the car.(race, lower, draily driver etc)

A good suspension test is to get a big dude (like 220 lbs) to push down the back/front bumper of your car. It should go down, up, and then settle. If not, you need new shocks. Also its easier to find squeaks when you have someone drive your car and you sit in the back. Thats how i found a few of mine. My rear trim, the piece that covers the talights and trunk latch, was actually rattling. And the rear speakers werent screwed down, and made annoying sounds when the stereo was on or at certain RPMs