You know, I'm dealing with this same issue right now. I've got a 241 as well. So far I've been dealing with the intake system because it was chock full of leaks; the dipstick was leaking as well as replacing one hose and elbow. My mechanic managed to clamp one leak (which I think did the trick) and repositioned a hose to fix another. It looked like the leaks were sealed, however I'm still getting the check engine light when I rev up just a bit over moderate acceleration, as well as when I start it up for the first time in the morning, etc. I am hoping it's not the EGR valve or regulator as they're both about 160 bucks and I'm still just a student here - that's alot of money to me. I'm really interested to see how/what you do - and I'll let you know how I do as well, we could very possibly have the exact same problem.

David
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1995 850 Sedan, Naturally Aspirated, 142k mi