I dont want to by a new lock and key.
I know theres a way to bypass the key decoder module.
Can anyone help me with this?/

 

Can't really bypass the module without reprogramming the computer, but you can bypass the resistor chip on the key and keep the module happy. Here is the procedure for a 4th gen car, but it should also be good for a third gen cars:
http://shbox.com/1/pass_key.html
http://shbox.com/1/vats_bypass.jpg