1998 225 hp -cdi ?

[lapdancer]

I have changed the stator and hi-pressure fuel pump on this engine and am still having complete shutdown after running for 5 min-30 min . After stitting for several hours it will crank up but will only run( 3000-4500 rpm) for several min.
When running it runs pewrfectly with no missing. My mechanic seems to have guessed incorrectly with the stator and fuel pump changes. This has gotten pretty $$$ and am thinking that this has to be electrical.. not fuel.
How can I deterime if the cdi is causing this sporadic failure ??

[boats.net]

Test it when it quits, check battery voltage to ECU on engine, check for spark at plugs and check fuel pressure.