F23A1 random misfires under vacuum

selttijcmanit

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Like the title says the car misfires a bunch under vacuum; while it sounds like a dragon grumbling out the hood exit, was wondering if it's normal in a stock engine.. Maybe you don't hear it because of the catalytic converter and mufflers? It happens during deceleration from >30MPH, I found an FIC I'll be installing soon but wanted to make sure it isn't a faulty MAP sensor.. (Could it be engine braking?)
 

selttijcmanit

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Aug 20, 2017
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YourMomsHouse
Also there seems to be a lot of pressure in the valve cover, oil occasionally sprays out the plug boot seals, added a catch can and filter but it didn't help much.. The PCV doesn't go to the IM anymore so it shouldn't be related to the misfires; I did clean the oil out of the plug holes and try to seal them but what is causing this pressure??
 
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