Process is stuck

Hi All, 

a process which took about 28s to execute takes more than 4 hours to complete now,there is no change in execution plan for this sql,

attaching the awrsqrpt report for the sql also the sql monitoring report,the table on which it hangs has stats uptodate ,it is partitioned & subpartitioned  and sized at 330g ..i have gathered stats for partition wise on this table with dbms_auto.sample size

the statement,

CREATE TABLE Q$_Q_FC_AGG_AVG_TMP NOLOGGING AS SELECT /*+ USE_MERGE(TMP,AGG) */ /*+ NO_CPU_COSTING */ agg.business_unit ,agg.project_id ,agg.activity_id ,agg.resource_type ,agg.resource_category ,agg.resource_sub_cat ,agg.country ,agg.foreign_currency ,agg.q_proj_currency ,SUM(agg.FOREIGN_AMOUNT) AS Q_SRC_AVG_BILLED ,SUM(agg.Q_CONS_AMOUNT) AS Q_CON_AVG_BILLED FROM PS_Q_proj_res_agg agg , PS_Q_FC_AGG_TMP24 tmp WHERE tmp.business_unit=agg.business_unit AND tmp.project_id=agg.project_id AND tmp.activity_id=agg.activity_id AND tmp.resource_type=agg.resource_type AND tmp.resource_category=agg.resource_category AND tmp.resource_sub_cat=agg.resource_sub_cat AND tmp.country=agg.country AND tmp.foreign_currency=agg.foreign_currency AND tmp.q_proj_currency=agg.q_proj_currency AND agg.contract_type IN ('FULLSERVICE','UNIT','FIXFEE','CUSTOMERMANAGED') AND agg.analysis_type IN ('INV','BAJ','DSC','FBD') AND agg.q_tran_type='PC' AND agg.activity_type IN ('TIME','FFS','TMCUR') AND to_date(agg.Q_year || '-' || agg.Period || '-01','YYYY-mm-dd') BETWEEN to_date(2013 || '-' || 5 || '-01','YYYY-MM-DD') AND to_date(2013 || '-' || 10 || '-01','YYYY-MM-DD') GROUP BY agg.business_unit,agg.project_id,agg.activity_id,agg.resource_type,agg.resource_category,agg.resource_sub_cat, agg.country,agg.foreign_currency,agg.q_proj_currency