8r sn 6yz00839 engine ecm problems

tractor was rebuild apx 5000 hr agao new all new wire harness was done by cat dealer at that time remaned all ecms since that time cat has replaced 5 yes 5 engine ecm all have given different problems . have had 3 different techs work on it all cat field service . I feel we are fixing the problem but not the cause .told them Friday no more reman ecm . will try a new one next week . but feel we are missing something . any one had this problem

8r sn 6yz00839 engine ecm problems