Hello Paul,
In this situation I would drop the gaps to 0.65mm and see if it improves:

If It does:
You have an ignition gremlin. Suspect the HT leads / cap / rotor or voltage deficit to coil.

If It Doesn't:
Chances are you have a signal error. Suspect phase or crank sensors.

The PP8's you have are outstanding for stage 1 and cannot be bettered. Period.
Ensure you bought the LT model PP8s as the gap on the ST model PP8s is 1.2mm.

Your fuel leak is common, that piece of pipe regularly fails mate, just replace it before condemning the regulator. Chances are it always leaks under load as the fuel pressure on your car is around 1.5 bar higher on boost than it is at idle.

Regards pump voltage. Only check this ON BOOST at above 4000rpm.
The readings obtained at idle are largely irrelevant.