You have a short-term problem here that you are going to have to resolve pretty quickly or it will do long-term damage to your engine.

I'll leave the solution of this short-term problem to others on this site who are far more expert than I.

But long-term there is one thing you can do to mitigate this problem, in fact, eliminate it, and that is change to synthetic oil.

I had the same problems that you and other have had with their 850s gunking-up. Every time I changed the oil I would take out the flame trap and it was caked solid with hardened bits of burnt oil.

After replacing my engine as the end result of this problem, on my replacement engine I have used Mobil1 exclusively and changed the oil and filter about every 5,000 miles. I still have the flame trap in, and I look at it at every oil change, and I have never seen anything in the area of the flame trap resembling the hard crud that I used to see when I used dino oil. There is no gunk, no hard bits, nothing but relatively clean oil.

Where I used to pop the oil filler cap and see darkened rocker arms and other components, now I see clean components bathed in translucent oil.

There is no improvement I have made on any car that appears to have had a better payback than switching to synthetic. All of my cars now run Mobil1 and I recommend it, or an equivalent synthetic, to anyone who will listen.