Crank Shaft Position sensor is the primary source for RPM data for the computer. BUT, Tach signal is usually done off Cam signal, because it is much more simple to time off of, at least historically... That said, I could be totally wrong.

You saw my justification as to why I though you should spend time on the cam position sensor. Again, my conclusions could be wrong...

You may have an intermittent signal in the wires leading to the PCM as well. If you have a pin out of the PCM connector it is fairly trivial to test for continuity between the PCM and CPS connector...

PCM's are expensive, but very reliable. I would exhaust all avenues (cam and crank sensors) before assuming a bad PCM;More so because it would be a problem with a sensor. Sensors are low voltage inputs to an analog to digital converter. Usually you have some sort of power electronic failure, like an injector/coil mosfet.

Good luck, This one is turning out to be a bear.

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