Hi
A few questions.
Did you let it get thoroughly up to temp before this happens?
Did you flush the fuel tank and install new filters, ideally before and after pump?
Have you installed refurb kits for Webers?
Powerspark do a range of coils, depending if you have standard electronic ignition, then I seem to remember the coil has a ballast resistor and the coil resistance is 1.5 ohm, no ballast resistor the coil is normally around 3 ohm.
I am also assuming you have checked idle speed timing of the distributor?
Peter