I've had some intermittent issues on my wagon relating to fuel. Occasionally on cold (ok so I live in California so 40F isn't REALLY cold) mornings the car won't start. When I turn the key I can tell if it's going to start or not because I either can or can't hear the hum of the fuel pump before clicking it over to crank the engine. If it won't start then, it will usually start later in the day when it warms up.

Things I've done recently:
Fuel filter, new copper/brass ceramic fuses (cleaned all terminals before), new KAI (german) fuel relay, replaced underhood 25a fuse and holder with waterproof marine grade unit, new crank sensor.

Yesterday, when it wouldn't start I jumped fuse 4 (each side individually with fuse out) to fuse 6 and could hear both pumps hum. I have a white label #933 ecu so I'm thinking it's not likely to be the problem (please correct me if I'm wrong).

I should add, that before I started changing the above parts out it lost all power 2 times over the course of a few weeks on the freeway (both times I could eventually get it going). It hasn't done that since the changed parts put it's worth noting (and I suppose might happen again or be related).

Any help you can offer would be greatly appreciated as I'm really pulling my hair out over this.