my rear section is soft, it bumps hard even I cannot seat no one in the rear seats...some people say they are bad coils some say bad shocks...my 2004 rx is the sporty one, premium package in some countries...do the coils can go bad?? is this common?

 

yes your shocks and springs can go bad after this many years

 

I just checked today and the shocks are not oily, just dirty from normal dust/slight mud and the passenger side shock is about 2 years old...