My buddy has a 86 325es,we pulled the eta engine with the harness and ecu out,and then dropped in an 87 325is engine with it's "i"harness and ecu.Ran fine for about a week then wouldn't start,or if it did it would die out suddently while driving.So we put in another "i" ecu in it,been running fine for about another week,then it's acting up the same right now.By the way I did put in the "is" instrument cluster when we did the engine,if that helps.Is there some thing wrong we did during the "is" swap?Any help is appreciated.