Hi guys, I'm trying to diagnose a 2006 Ford Freestar with the 4.2 of which the engine runs rough with a P0301 check engine light indicating a misfire on cylinder 1. Apparently this engine is known to have plugged EGR injection ports which require pulling off the intake to mechanically clean. To test if it was an EGR issue causing the misfire, I unplugged the vacuum line going to the EGR valve and miraculously the engine runs smooth. Before spending the effort pulling the whole intake manifold apart (it's alot of effort), I'm wondering if there would be any value in trying to inject Seafoam down the intake or vacuum line on the EGR valve? Would this knock off any of the carbon? Sorry if this is a noob question as I'm not that familiar with the EGR system. The intake manifold gaskets are also quite expensive, but they look like they should be reusable. Thanks!