"Locking row for access" is only for selects, insert/delete still set a write lock.
Do the ETL jobs use PI access in multistatements or PACKs?
Which ETL tool? TPump? Then the SERIALIZE option might help.
The ETL tool is datastage.
The ETL Delete query is not based on PI.
DELETE FROM ETL_LOG WHERE ETL_Bus_Dt = 'Date' and ETL_Proc_Id = '1' and ETL_Trfm_Id = '1'