Misfire at cruise, popping/afterfire at 3000RPM

TT5.9mag said
As you know, new don’t mean good. I’d check the new one as well.

Sigh...I know. I honestly don't know why I decided to get a new distributor without checking my old one, but that's in the past.

Bewy said
Disconnecting the throttle linkage of the end carbs does not remove them from the action, if that is what you have done. If the fuel line is still connected, they are still getting fuel, which could be leaking into the engine. The fuel line ~~need to be disconnected for complete isolation or the carbs removed.~~

I ran the car with the outboards completely removed from the car. They were sitting on my workbench as I drove away.