Can anyone help me with this one please? I have a 2009 320i coupe with 38k mileage. I have been having an issue for last 9 months or so. Here is a synopsis: When idling, every 5 seconds or so, the engine trembles a little as if it might cut out but it never does. This is usually around 600rpm and you can see the needle jump at the same time. Is seems to cough/hiccup a little whilst driving (or maybe misfire) but at high speeds on the motorway, there are no symptoms and it runs fine. During it's last MOT emissions test at the end of 2017, the lambda reading was excessively high for around 2 minutes and then came down to an acceptable level. About 2 months ago, the check engine light came on as it began jerking whilst driving. The scanner came up with "misfire on cylinder 2 and sulphurized catalytic converter". The coil pack was changed as were the spark plugs which solved this problem and cleared the code. But, the general misfire whilst idling and at driving 30mph or so/during acceleration is an ongoing issue so something isn't right and I wonder whether this caused the problem which brought the engine light on. Any thoughts/experiences please?