Rough idle and rough cruising, especially with light acceleration. E042 Code

[2seater]

Your bypass was/is a good idea, but you may be able to shorten the repair without going all the way to the ECM. The usual damage is in that harness on the engine and the plug to disconnect it from the main harness is behind the power steering pump. Try connecting your jumper near the plug location rather than through the firewall. Just a thought.