[Very Frustrated]

This television is a 2003. It keeps going on and off. Iti will stay on for a few seconds then go off. when it finally comes on after toggling back and forth with the on and off button, it will stay on for sometimes 3 hours, sometimes 3 minutes. Does anyone know what my problem is? I am short on cash and cant afford a new one right now. when it comes on it has still an excellent picture, then will kick off. please help