02 error

have purchased new ac delco o2s witch are denso. have two wirinf harnesses.and 3 e92 ecus.have had this setup running before l83 6l80.cant get my 02 voltage down to normal no matter what i have tried or asked.was told o2 e92 or wiring. have verified all these over an over for weeks now.last logical conculsion would be mvpi2 controller.it seems to operate fine in another vehichle.so for all the exsperts what would cause this issue iam new but very knoledge an have taken many hrs of research to accomplish this swap.an to learn this newer can bus tech.just to wind up with a 15000 buck hunk of scap.