I have a 04 Ford Taurus DOHC with coil on plug, showing codes P0351 P0352 P0353.

The first 3 seconds after start up it runs smooth but once it idles down and its back to misfiring and misfires thru the entire rpm range. Cyl 1 has no change at all when the coil is unplugged. Tried new plugs. Switched coils from cylinders 1, 2 and 3 with 4, 5 and 6 still same problem same place. It runs like its on 5 cylinders and at times it acts like another cylinder is dropping out. I pulled each coil and visibly made sure there was spark although im not sure if its firing in time or not. Ive checked wires from all connectors back to the pcm and they all checked out fine. Ones shop said it just needed a pcm so I got one and it runs exactly the same so that was 300 bucks wasted. I bought this car cheap from a friend thinking it would be something simple like corrosion since he said it started doing it within mins of washing the engine at the car wash. I have found absolutly no corrosion anywhere. What else could it be?