N42 engine recently had chain and guide replaced new valvetronic vvt spring replacement (only one) Due too breaking

Misfiring on cylinder one

new coil on cylinder one and is stil not idoling when hot.. when cold it’s fine but once drove I come to a stop and it cuts out or the revs are bouncing from 1000rpm to 400 engine codes are 2852 2866 27bb any help would be great feel like I’ve tried everything and I’ve gone to far to give up now after new sump gasket and rocker gasket new key and barrel due to not working whilst fixing everything els

also engine now smokes from the back of the engine once turned off Asif the gasket for the rocker was leaking but it’s seated well and brand new


I had no problem like this till I done the guide and chain and when recovered the plastic guide from sump I found the vvt spring that had broke sorry for that bad grammar and not the best at explaining things any help would be great kind regards giorgio