Burned oil smell

[Fusion]

I've been having a burned oil smell in the cabin the last few weeks and I can't figure out wtf its coming from. It usually happens when I'm in gear downhill (shift down to engine brake).
I have a new cam cover gasket. The only "flimsy" thing is the vent hose on the cover, the O-ring is probably dead.

The worst thing is even if I stop the car 5 minutes later, stick my head in the bay, can't smell shit except some gas fumes.

[sector6]

I bet if you could see your exhaust during this "downshift" you would see smoke. My buddies E30 did the same thing and smelled like burnt oil in the cabin. Smoked like a bitch when downshifting. Worn valves or rings?? I'm not an expert.

[Adrian_Visser]

If it smells like smoke when engine braking it is probably the valve stem oil seals or valve guides. The valve stem oil seals tend to go before the valve guides.

To be sure get a friend to drive behind you down a hill and use full engine braking if they see/smell oil you'll know for sure.

[Fusion]

Not losing any oil btw. Is it a hard job to replace the seals/guides?
Any other possibilities? I'll look more for a leak, I guess it would have to be getting onto the exhaust to burn.
Oh and the hose from the cam cover to ntake is like really mushy, what if it was plugged?

[Fusion]

Update:
no smell when I fully close all air vents, so my assupmtion is that it's not exhaust fumes entering through the trunk area, correct?
If the valve seals were bad, wouldn't it stink at least a little even in idle? I had a car with an I4 8-valve engine that had bad seals and it smelled like shit in idle. The M50 in idle and operation temp smells great, just well-burnt gasoline.

And it started when I changed the fuel pump. No idea why that would smell like oil, but when engine braking, the injectors shut off and incoming fuel is returned to the tank right?