Thanks everyone who replied. I did searched through this entire forum. I looked through several hundreds of posts, took me several days. I did haven't found anything that would apply to my problem. As far as catalyst & o2 sensors - they all pass. That's the thing, all tests have been passed and cleared except EGR.

I haven't contacted Eurocharged, but it occurred to me in the past that reflash my ECU (even if I don't need extra boost), may reset something that could fix the problem, but I want to leave that as a last resort.

I apologize for cross-posting to another (previous) post, but nobody replied to me in several weeks there. That's why I rephrased my problem in this post.