[kev0]

Originally Posted by 86TOYO2k17

An abundance of unmetered air (IE a leak post maf sensor) could cause a misfire and the fact that it is one cylinder it would make sense that the gasket around that cylinder is leaking letting extra air in under vacuum (IE at idle when boosted) only that cylinder would be effected. But it may not be a faulty gasket and just a dirty surface and or scratched/scraped surface not allowing proper surface mating. Also be extra careful not to get any of that inside the cylinder head.

A thorough inspection and cleaning of the surfaces and gaskets. Then double check every single hose is fully pushed on and clamped. Make sure brake booster is installed correctly (this could be the other fault code) . Go over every install step and thoroughly read and fully understand exactly what it wants you to do and why before moving onto the next step. Then reflash tune. And give it another shot.

I appreciate you!!