what causes intermittent loss of cmp or ckp? what do I need to replace to fix it?

The CPM stands for Cam Position Sensor and the CRK stands for Crank Position Sensor. It would be really helpful to know what engine you have in your vehicle so I could look at the wiring diagram, but the Cam and Crank Sensors do fail. It would be best to study the scan tool data when the car is stalling, you want to see a loss of the signal data from either of these sensors, that would really 'ice it' or verify the cause of the problem.

It is NOT CRK