code 300 misfire

I’ve changed all my Spark Plugs, changed all my Ignition Coils, got a new EGR Valve put on, and still my car is misfiring. I’m not sure what the issue is it just started messing up when I hit 160xxx miles... I think I’m going to just sell this car I’m sick and tired of spending my whole check to...

hello all experts, need your help SXT 3.7L 2008 1 month ago I had code P0300 (misfire), replaced all spark plags, replaced intake seals, and solved the problem. Now again I have code 300 and code P1129, same symptoms, engine hesitate at low REP , I removed the intake manifold and sow some...