What's the betting that the previous owner never really gave Big Suze any long runs or got her up to much speed ? That's usually when things like that happen. Anyway, looks like you've got it all sorted. I wonder exactly how many of your arms and legs a garage would have charged you to do that lol ?
I'd almost guarantee it zed I got big suze as a ULEZ refugee so I'm guessing school runs and shopping and 20 years of soot! She's in good hands now, I only use premium diesel, I routinely use the good fuel system additives and I'm not scared of scraping out some nastiness! Garages? Pah!