Hey thanks for all You're help, I've had the compression tests all serviced and done and its not the problem so will try the air filter and give the injector a clean! Cheers bud, really appreciate it!

Hey Smokey its black smoke and I can see the Diesel externally, will it cost to fix or is it something as easy as tightening a seal?

I have 1 out of the 4 injectors leaking, would that make it stall occasionally and smoke quite bad? Cheers