Check the voltage to the CPS. This little sensor generates a very low level signal by detecting the magnets in the crankshaft as they come by. Really cool, old school design called a Hall Effect sensor.
The distance from the sensor to the crankshaft is critical, and usually set by design. If there is a poor connection anywhere in the circuit that feeds the trigger voltage, or in the output signal, you will drop pulses coming out and get a fail code.
Not to start a war here, but this is one of those sensors that is best bought from the OEM. An intermittent output from a cheap CPS will drive you nuts. It is also possible to get a weak output at high RPM. As the crank magnets pass through the sensors magnetic field at a faster rate (think of it as trying to watch a hockey puck passing in front of your eyes!) the output pulse can get shorter or smaller. If the ECM doesn't see the pulse, it assumes the engine is not turning and shuts off the ignition and/or fuel injection.
I had to track this down on a 4.3L GM engine. The engine ran just fine up to 4500RPM. Just above that, it stumbled and then shut down, only to recover once the engine speed dropped. This can get really exciting during a highway speed pass.
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