I'm trying to help out a friend who owns an '03 Chevy Caprice (Holden Statesman in Australia; LS1 V8). His transmission is misbehaving; it doesn't want to upshift unless the engine reaches a high enough speed like 4000 RPM.
He recently had the transmission fluid refreshed and recently observed metal flakes on the transmission dipstick as well. While it is likely that the root cause of failure is mechanical wear and tear, he is wondering if the behavior could be explained by an electrical/electronic issue such as a bad sensor.