My name is XXXXX XXXXX I can help. This is going to be a fault with the fuel pump itself.
Although you have not been able to verify it, I have never seen your symptoms, especailly as intermittent as you described, be anything else. Any chance the problem happens more during a weather change? temperature change in your area? This is another factor that points to the fuel pump. Replace the fuel pump, located in your fuel tank and the problem will be fixed. This is not a shot in the dark.
Let me know if you have any more concerns about this question, or my answer, will be very happy to help!