I have 2016 RXS 860I that will rev up only to 3000 RMP but not much more. The engine idles fine and runs smooth. Gas is good, plugs good, air cleaner Ok. Took the gator to local JD shop without any fix. They believe I had a bad ECU/Throttle body as they could not code read it for codes. New ECU installed and they could read ECU without any increase in RPM. All looked normal with no active codes or stored. Fuel pressure tested 45psi. Throttle actuator & engine timing all in specs. Any thoughts?