Is the idle rock solid at 850-ish rpm or is it fluctuating? 750 -950 rpm once warm?
You mentioned in your OP that it doesn't wake up until 4,500rpm and higher?
does it seem to be gradual below that, hold the revs then increase onwards all of a sudden after that?
If it is, remove the induction hose, clean the throttle body thoroughly, plenty of "how to's" on here and pay attention to the difference between CF2/ CF3 proceedures....
Inspect the bellows for any tiniest of splits from the maf to throttle body and refit.
Remove the MAF multi_plug connection and check the pins, are they nice and clean? Spray with electrical contact cleaner and refit.
Do the same now to the O2 sensor connections.
Check your earth straps, paying attention to the ECU one in particular,the NEG battery earth to inner wing body & gearbox earth. Remove, clean, refit.
Do a soft ECU reset (miracle cure).
Now take it for a good spin of 25 miles + and you will see it should return what you are expecting.
Never completely rely on ODBII codes to tell you everything, they dont....! Listen, Feel and go with Gut Instinct and common sense too
Or... You can continue reading codes till the cows come home and ignore the above, your choice