Yes, I removed my egr valve and cooler, replaced with egr delete. At the same time, removed inlet manifold for cleaning.
Thick black sludgey build up. Scraped off what I can from inside, left to soak in degreaser.
Then attacked it with oven cleaner and a good scrub. Think I also used some petrol.
Ultimately, a lot of scrubbing to get it clean.
For the egr valve, carb cleaner should do the trick.
Jas