Removing the intake from a diesel and cleaning it is a common thing to do. I have a parts cleaner, you know a "solvent sink", which makes the job not to bad. If you don't have facilities to clean the manifold, it will be a problem.
If you know an automotive machine shop with a Jet Wash safe for aluminum parts, that would be a good way to go.
'84 Euro 240D, 523K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in