Hi all . I’m new to the forum. I’ve not had a golf in years so I purchased my mk 5 gti dsg. Car had done 150000 miles with most history. Now after 3 weeks it’s developed a miss fire , when driving hard it misses and engine light flashes. But once speed reduces it goes away. I changed spark plugs and then the issue has got worse ! It ticks over terrible and has epc and engine light on. I noticed plugs 1.3.4 were denzo and all had brown markings on the tips , but no3 was a older looking ngk thus looked all crusted up? Any help would be great as I Dnt want to waste money where possible. Thanks