I would certainly start by using the correct fuel regulator, even a well knackered pump would produce more than this at idle if it is driving ok, as there's next to no demand idling.
You are playing with fire using a pressure reg that almost certainly has different characteristics than those of the expected(by the chip writer) std fuel pressure reg, unless you've had it mapped on these, just get the correct pressure reg, it is also adjustable so can be set to the correct pressure.
tabetha