If oil burning it is likely low on compression. That might be borne out by the fast cranking speed.
Best start with a compression test. It could be leakage past the pistons or it could be valve recession (as JS was suggesting). Or both.
Could be injectors, too. Or were they sorted at the same time as the pump? Is the pump timing correct?
Is the manifold heater working? And do you operate it for cold starts?
So many possibilities...