Yes, the ECU could be faulty. Sometimes with age it develops micro-cracks in the bus-lines and that leads to similar errors

Try swapping it out with a working ECU and see if this would solve the problem. Just clear the errors first

Another suggestion since you have already replaced the engine harness, the VVT motor, and a couple more parts, is to inspect the timing chain, timing chain guides, and your Eccentric Shaft Sensor
Make sure the chain guides are not damaged and the chain is tight and properly tensioned

Look here