my gt4 has water problem Options

[Ronnie5]

[size=3][b]Can anyone help??,
I have a celica st185 gt4, Im am having problems with water staying in the engine/radiator when I drive it slow its fine but when I put my foot down and then stop wait a minute and switch off I have the contents of the radiator pour out through the expansion bottle which make the car overheat when I am driving it, I have changed the rad cap which makes no diffrence I can also hear the water flowing and bubbling inside engine
, once cap is off its as if the car breathes! water comes out and then goes back down over and over again until cool.
Can anyone help as I cant afford to take it to a garage!..

[Supersprynt]

Whats your temperature sensor showing? You probably could use a thermostat.