If you are still getting the P000A code after replacing the N205 valve, it may be the VVT adjuster itself that's faulty, or one of the plastic oil control rings in the chain cover has broken, or possibly an oil flow restriction. Has it had the chain and tensioner done yet? Could be a good time to do all that.
I know what you mean about the idle feeling like a misfire, but it's just lumpy from not running optimally. It will only log a hard miss, like a failed coil or injector, and you would definitely feel it running on 3 cylinders!