the timing chains on gen 1 mini is very easy to set up cant see how anyone could get it wrong,, you have 3 links coloured and two side by side arrow marks on bottom sprocket and one mark on top sprocket really is a no brainer ant tech would totally not get that wrong its so in your face as such, unlike the gen 2 r56 princes engine they are easy to get wrong, the knock sensor multi plug is bolted to one of the bolts around inlet and ss i know i always unplug them to avoid damage,, but would deffo give a code if not connected,,
its common after head gasket failure for the 02 sensor to get damaged also the cat as well, its also common the badly running engine before the ecu learns the setting of the adaptations and good idea to reset them like said before how to, i done one last week and fitted a high lift newman camshaft in it and until i reset the ecu it ran all lumpy and would not pick up right, after reset then a hour long run through the rev band its back better than right again,