Whack looking waste gate setup.
But i'm sure you already had another thread and asked all these questions before.
Simple answer, get someone who knows how to make up an exhaust, make you a new dump pipe.
Get him to weld a small section pipe directly to the waste gate with a v band flange on it. Then another v band flanged bit of pipe for the actual waste gate pipe. Then plumb it back into the dump pipe down stream or atmo vent it, What ever you want to do.
Go to AM performance, he's in the North as you are AFAIK. Expensive but good work. You'll be happy.
ECU only looks at the 02 sensor under cruise and light load conditions so you wouldn't have even noticed it being disconnected. Maybe excess in fuel consumption. But chances are the 02 is knackered anyway.
No offense, but you appear to create thread after thread about why your car doesn't idle correctly / miss fires. But have you actually done any of whats been suggested? Like changing your coil packs, igniter, coil pack loom, cleaned the AFM, checked for vac leaks, made sure the AAC valve is functioning correctly etc etc.