Performance Tuning :: Lost Index From Second Execution Time?

The problem was describe:

- First time to execute: Using all indexes on 2 tables

- Second time to execute: Using only indexes on first table, full table scan on the other

- Third time to execute: Do FTS on both of tables.

Now, I show the objects and relate information here:

The Tables:

system@dbwap> select count(*) from my_wap.news_relation;

COUNT(*)
----------
272708

system@dbwap> select count(*) from my_wap.news_content;

COUNT(*)
----------
95092

system@dbwap> desc my_wap.news_content;
Name Null? Type
----------------------------------------------------- -------- ----------------
ID NOT NULL NUMBER(11)
SUBJECT NOT NULL VARCHAR2(500)
TITLE VARCHAR2(4000)
STATE NUMBER(1)
IMGPATH VARCHAR2(500)
ALIGN VARCHAR2(10)

[Code]....