A buddy of mine has a stock DBC 5.3/4L60 in his 56 Bellaire. Engine runs great, but does not trim due to the O2s staying at 450-480 all the time. I loaded a complete stock tune in it with the same OS thinking something was turned off keeping it from going into CL, but nothing changed. We replaced both O2s and still no change in the MVs. Could this be a grounding issue through the O2s?