That's an awful lot of oil to get past the rings!!!! Did a compression check get done?
The oil level will not cause the engine to run rough or die unless it is seizing or the crankcase is full of oil.
Just how much oil do you see in the exhaust? And can you supply a picture of the plugs.
I would think that for that much oil to "go away" that it is getting to the exhaust via another route and about the only way that will happen is something is cracked. Have you had a recent overheat or a freeze with water still in the block.
That much oil burning 9ff would leave one heck of a "Batman smoke screen" be hind you.
Dave Neptune
