Stone Monkey

Advice wanted

Hello I recently bought a 2010 Subaru Impreza hatchback Diesel online due to Covid.

Great in the snow we had but its producing large amounts of black smoke and using too much fuel.

Not sure where to start, fuel pump, fuel injectors, EGR valve, DPF, engine flush!

If anyone has an knowledge of what I should do first to solve the issue if would be hugely appriciated.

Cheers

Stephen