Hi

Did it ever run in less then 5 minutes ?
(your users are very patient to wait for 5 minutes )

Have you thought of a MV

Code:
CREATE MATERIALIZED VIEW LOG ON MAM_ATTR_STRING_VALUES WITH ROWID

CREATE MATERIALIZED VIEW MAM_ATTR_STRING_VALUES_MV
CLUSTER m_lt_li (id)
REFRESH FAST ON COMMIT
ENABLE QUERY REWRITE
AS
SELECT SV65539.ID 
FROM MAM_ATTR_STRING_VALUES SV65539
WHERE SV65539.LOWER_CASE_STRING_VALUE LIKE LOWER(CONVERT('%813982%','WE8MSWIN1252','WE8MACROMAN8'))
AND   SV65539.ATTRIBUTE_XID=65539