I had a leak in a strange spot thats hard to notice... the cam angle sensor o-ring. But that was my case. As far as the missfire thats a common code that could be anythinglike fuel or intake filters, leak on the intake end(aftermarket intake system coupling is ripped), injector cleaning, bad vac hose, ignition wires plugs, you would feel hesitation and missing if it was a serious miss from a coil pack problem.

...and im with Got_bst? on 420a quality! Very reliable and easy.