15 Ignition Output signal
That could be a bad ignitor in the distributor. But it could also be the wiring from the ECU to the distributor. That's the 'signal' where the ECU tells the ignitor to fire.

43 could be caused by low fuel pressure, like plugged fuel filter or failing fuel pump. Can also be from dirty injectors, dirty wiring connections to the injectors, or a handful of other things.

Deal with 15 first, because if that's causing misfiring, that in turn might be causing the 43.