Happy new year!

I have a small problem with my x330.
When starting with a cold engine, she runs and idles fine.
After a couple of minutes she starts idling rough, like small misfires.
When on the open road and driving with a steady speed, you can feel she is losing power sometimes. I have to apply power in order to make that go away.
I notice when I unplug the maf, she idles very nice though a bit slower on the revs and power but this is expected when not having the sensor plugged in.
I have changed the maf with a working one from my other x300, but this does not change the rough idle and running. As soon the maf is not connected and she switches to the default ecu settings she runs 'okay'

The big engine fan is running when I turn on the engine, something my x300 does not do.
Can anyone explain to me what other functions or settings are being defaulted when you unplug the maf?
Should I try another maf from another car or is this a typical fault for a particular sensor? e.g. temp/o2 sensor?

Things I have changed so far :
-new plugs
-new coils
-new oil
-new oil filter
-new gas filter
-new air filter
-cleaned the maf, throttle body (was already super clean)

Thanks!

 

Have you used the right spark plugs and checked the gab of the new spark plugs?

 

Champion RC12YC according to tsb, correct gab. Just a question, what has this to do when it runs good with my maf unplugged?

 

So many parts replaced and you haven't plugged an OBD scanner? Post some live data from when its running fine and when it heats up and stops running fine. When you disconnect MAF, ECU switches to default fuelling map so it could be an o2 sensor failing, could be other things, hard to say rly without seeing live OBD data.