Injector cleaning by adding a cleaner to the fuel will help by disolving varnish/wax deposits, so can give good results. However some insoluable particles which get past the filter can lodge in the injectors, and only back-flushing or disassembly can clean that. I had brown fuzz in the inlet screens of my injectors, so I suspected some could be inside the injectors. I made two injector back-flushing kits, thanks to some help from Scud, and can mail you mine if you want to use it.
...and the 5 Dec 2016 post here: https://www.v11lemans.com/forums/index.php?/topic/18805-brand-new-scura/&do=findComment&comment=215317https://www.v11lemans.com/forums/index.php?/topic/18805-brand-new-scura/&do=findComment&comment=215317