Intermittent Misfire 2000rpm

[Chapucero]

Good morning everyone, I am new to the forum, given up on the so called 'professionals' giving me wrong and expensive diagnoses! I have a 2007 1.9 dci (D/F9Q E8) that splutters or misfires at 2000rpm regardless of speed or gear but some days are worse than others and very occasionally it doesn't happen at all!! had a new EGR valve fitted and it was ok for about half an hour, used a quality injector cleaner a couple of times and it's ok for a day or so but then starts again. Had a couple of OBD faults cleared and again it was ok for a few hours but didn't last long. The garage now wants to send the injectors for testing/refurb which I'll have to pay for even if the result is that I need new injectors, I'm not convinced this is the best or only option, anyone help please, it's driving me nuts