mechanics advice required car running rich and misfires

[Cupra Ross]

Could be a duff injector.

Also, thoroughly check EVERY rubber/silicone hose connected to the intake manifold, including the 2 large ones that attach underneath it in the middle, I've had one of these split on the bottom before and you wouldn't have known by looking at it. You need to squeeze and feel all the way along the hoses, a visual inspection isn't enough. I'd put a fair bet on that one of them is split.

 

[Banzaiii]

A duff injector would then show as one black spark, right? In my particular case they were all equally run rich.

I also tried looking for bad hoses and vacuum leaks by spraying engine starting spray around the motor and following every vacuum line. It's a really good old trick, since the spray get's sucked in where there is a vacuum leak and you can here the motor rev up. In my case it didn't show zip though...

Sorry for hijacking the thread, but I reckoned we both have a similar issue and are equally interested in having it solved....