Update is slow

Hi,

The following update is recently introduced in one of the peoplesoft process, attaching the sql monitor report,  it looks obvious in the plan the cardinality of this  temp table PS_PRT_BI_TAO  is bad, it takes more than 4 hrs and still executing.. Version is 11203

i tried two things ,

gather stats on temp table at auto sampling - No improvement

Delete stats on temp table - dynamic sampling used (level=2) - No improvement, all other table cardinality is gathered appropriately,

Please give some pointers on this,                     

UPDATE PS_PROJ_RES_DEL

SET BI_DISTRIB_STATUS      = 'D'

WHERE PROCESS_INSTANCE       = 4957167