The problem is the EGR valve feeding exhaust and the crankcase breathing sending oil fumes back into the engine thru the intake manifold. This combination makes a mess in the intake manifold. Gasoline engines have gasoline in the intake manifold to continuosly clean it. Diesel engines do not.

You will have to clean the mess out and "FIX" the EGR valve. You might have to take the manifold to an automotive machine shop for a HOT tank cleaning.

P E H