[JimD]

You did not mention mileage but if you have a lot of miles on your plugs, that is where I would start. You have to remove coils to change plugs so it could be a convenient time to do them too but it is more part expense. The HPFP is kind of like changing the injectors. The theory is the misfire is fuel related. The HPFP is a frequent issue which is why I think others are mentioning it. I don't understand your last sentence but if it means you've had the plugs replaced recently, then it depends on what you want to have replaced next. Coils and injectors and the HPFP can be tested but it is beyond what typical mechanics do. Most of them guess, replace parts, and want paid. If it takes more parts to get the issue resolved they want paid for them too.