Odd Misfire - 3.2L Alfa GT

[NToff]

Hi all,

Lately I've started noticing a misfire on my 3.2L GT at idle only. It seems to be worse when the engine is cold, and conditions start to improve as the car warms up, however the misfire does not go away (can still hear and feel it even when warm). At times when idling I do get random MSCF engine lights resulting in stored codes (i.e CEL flashing and beeping, and then disappearing). As the car starts moving there is no misfire whatsoever. It is only present on idle and low RPM. There is also a noticeable miss or two when releasing the clutch to take off, as the RPM's dip. The stored that have been pulled are;

P0300 - Random Misfire
P0301 - Cylinder 1 Misfire
P0302 - Cylinder 2 Misfire
P0303 - Cylinder 3 Misfire

I have taken it to my mechanics who have logged data using MES and cleared the stored codes (which eventually return), and are pointing either towards the coil packs or the right pre-cat O2 Sensor as this is banked with cylinders 1-3. I have disconnected the MAF and instantly had a negative effect on the running of the engine, so I'm pretty sure this is all in check. There are no vacuum leaks, and the spark plugs were changed along with the timing belt and water pump about a month ago and the air filter is brand new. Having a look through the invoice history of the car, there is evidence of all 6 coils being replaced (113,000kms), and both post-cat O2 sensors (175,000kms). Car has 177xxxkms.

I'm starting to lean towards a faulty O2 sensor as it's a little suspect that all 3 cylinders throw codes at once, however any options would be greatly appreciated!

Many thanks!