Sop as the car warmed up, the fuel pressure increased?? How can this happen when the fueld pump does not really se any heat -- it's trunk located I think. I'm not too sure on that.

I'm thinking it may be more of a flow sensor in the electronics. Maybe Volvo was smart enough to have a circuit path telling the engine not to rev too high if the oil is cold. You don't want to be pushing cold oil to a turbo or the seals will go instantly.