Ok. I had one broken ignition wire and the other ones were visually in bad shape. Changed the wires but same results.
Too high HC (200) and CO on idle
Then low HC and CO on 2000 rpm and interestingly 1.5% O2.
Could a loose chain be the cause ? I haven't tightened it for 30Kkm
If combustion gets a little better, then HC lowers a bit and consequently CO or CO2 increases a bit. (HC is unburned fuel!)
Now, since both HC and CO are high , you could go to an Alfa Romeo service dealer and use the tester to check if all sensors and overall compression is o.k.
In Greece, this costs about 30€.
If all sensors are o.k., checK if all bolts in the exchaust parts before cat, are tight.
Also, check if there are any wet spark plugs. If so, then sth wrong with the combustion in the corresponding cylinder.
Also, should Know, that catalyst's life of your car is at the most 200KMeters~120Kmiles.(If high CO, usually catalyst is dead.However, you have low CO on high rpm, so catalyst might not that bad).
So, for a start, check the sensors in a tester and also your thermostat!
Also, check the spark plugs for water, or other deposits like oil .