I had a similar problem on my P60SE (6.0 ecu). I sent the engine to Jetcat. They upgraded the ECU to the latest 6.0 version (6.0H at the time) and the problem went away. Of course it is intermittent and it is hard to know for sure that the problem is definitely gone.

I did a lot of research on the subject and my conclusion was to:

- check all fuel related stuff (solenoid, pump, line, filter, tank, clunk)
- check that the rpm sensor wire is properly connected and has clean contacts on both sides
- make sure that the rpm sensor wire is not subject to electrical noise. You may want try routing it differently.

I hope this helps.

Arnaud