Citroen C4 1.6 VTi 5FW running rich and stumbling

[Off_Da_Wall]

Before I start I'm aware it's a Citroen and has the dreaded Prince engine but I'm stubborn and won't let it get the better of me.

So the car isn't running right suffering from the following symptoms: rich exhaust fumes, stuttering at low rpm(setting off and crawling is a pain), rev hanging around 2k rpm. The car seems to slightly improving as it warms up but still isn't right. If I get it up to a higher rpm in 1st and then shift then the rev hang isn't so apparent. The car has no EML present, but I have had it give me a P0420 code on longer drives. In terms of repairs, the vehicle has had quite a lot done to it just to get it to where it is now. Originally the car suffered from a constant knock sensor fault (ended up being a faulty ecu) and its original engine skipping a tooth on timing. The local mechanic did the timing chain and the engine would not run when timed correctly(The mechanic gave in and found a replacement engine to which he did the timing chain and the car would run.) The replacement engine was taken from a running car said to have no engine issues.

I'm at a loss as to what the problem could be but my thoughts are to check -

Camshaft vanos timing solenoids on both inlet/exhaust
Readings on the pre and post O2 sensors
Condition of the catalytic converter - is it blocked?
Consider carbon cleaning service

Lastest update-
I've uploaded a couple of videos and pictures of some live data. - https://photos.app.goo.gl/u7FEWxT2ijVQLVDr5

The car wasn't completely cold when I started looking at the live data so the coolant temp was around 50 degrees after idling for a while it got up to 85 ish so the coolant sensor seems to be reading correctly.

The car is showing a few codes -

P2178
P0420

I believe these codes are present because the ECU is from a c4 Picasso, the same car the replacement engine came from I just had it unlocked.
UD128
P0565
P1536

The coolant temp reference value being -48 degrees looked a little strange but I don't know, is that normal?

I also see that the upstream sensor regulation status stayed in a closed loop and the downstream sensor regulation status was open loop.

My question is has anyone had a vehicle suffer similar symptoms and how am I best troubleshooting them?