It started about a month ago i would very randomly get blinking CEL's (misfire on only 1 particular cylinder) and then it would go away and come back. Brought it into the dealer several times they never had the same issue but saw the code, Finally brought it in for a 4th time and they found a head to be cracked (only 7k miles). At this point ford told them to replace the whole engine, a week later here i am. Went to drive home running and sounding great, 30 miles later i accelerate and upon slowing down at the stop light the engine starts to shake REALLY bad and the CEL blinks again. So now the dealer has asked me to keep and eye on it and bring it in if it happens again. Anyone have any ideas what could be causing it? So far my dealer has been great and i hope they can fix this issue permanently. Also no mods at all are on the car or ever have been.