Hi Ivor,

I don't think you will see the whole picture with VAG-Com or did you mean Vaux-COM? You could lose compression intermittently caused by a hydraulic valve lifter sticking, check also EGR valve, insufficient oxygen usually causes black smoke but could get blue if bad enough. Did the injector replacement cure it for the the 5 days and if so where they good quality injectors? Reading the archives there are plenty of reports of faulty recon injectors out there.

Mark