I have a late 2015 Mazda 6 2.2 Skyactiv Diesel. The car has 79k miles on, with full service history. At 50k it had a new Turbo by Mazda. At 60k it had a new EGR Valve and Throttle body. At 64k (Jan 2022) it had a full Carbon clean by Mazda. The car has an issue, where after 30 minutes or so of driving, it starts to feel like it stutters and misfires under acceleration. If I turn the car off for half an hour or so, its fine again for a while. I've found out the previous owner actually sold the car because of this issue and Mazda quoted £3500 for new injectors as that 'might' cure it but they couldn't definitely say that was the cause. I've replaced the fuel filter as its due, but that hasn't made any difference. I've also noticed a clacking noise from the top end, very noticeable if I remove the oil cap, which I don't know if this is normal (I have a video of it but can't work out how to post it on here). Any ideas as to the cause, is it bad injectors or another issue. It's worth noting there are no warning lights or error messages.