I believe you both are correct. At approximately 2400 RPM the computer shuts off the fuel injectors to stop from over revving the engine.
I was not accelerating I had the engine brake on and was decelerating downhill.
My root cause failure analysis says that the transmission downshifting one if not two gears over sped the engine causing mechanical damage.
John and Sue from W. Texas
2001 DSDP, 3126B Cat
"the Oilfield PAID me to retire, so I did" :-)