could be a leaking head gasket and what happens is that coolant is leaking into the cylinder after you shut it down.When you crank it up in the morning it has to burn that coolant up there for skipping , then when it burns that up it runs fine.... Had a few 240 has this problem and it never ran hot but leaked into number 1 cylinder.... After i shut it down after about hour or so driving and took that plug out I could see coolant going back into that cylinder. I took a mirror and placed it over that cylinder with the plug out and yup it was coolant for sure...