It's pretty simple, it's called "bad connections." The thing is, the more things that are shaky, the more stuff gets added into the stew pot of "trouble." Now it might just be that the twisted wire connections at the ECU ground and at the ballast resistor ARE NOT the full problem, but they might be close to it. Maybe the carb is a little "off" and those twisted connections are causing poor spark performance. That may be the combination that "does" it or--it may be the vibration / movement of the engine moves one of your "twisted" wires just enough when you give it throttle, that connection loosens.
Fix the stuff that is obviously wrong. Then try and work through the rest of it.
