Hi. so about 2 months ago my civic overheated on the freeway and I found out that I had a leak in the radiator and had to replace it. The over heat issue is taken care of but ever since then the car has had a rough idle (bogging and rpm drops). I've replaced the fuel filter and spark plugs. the issue went away instantly after changing the plugs, but then a week later the problem started again.
today i pulled the plugs again to see what they looked like and they had the brown marshmallow look to them so they dont look bad. as far as i can tell there isnt a leak in the head gasket as there is no water or anti freeze in the oil. i was going to go pick up a pressure sensor today and hook it up to a spark plug hole to see for sure it there is.
anyways, i was just trying to find out if anyone has a clue as to what may be the problem. the car hasnt died and drives fine as the rpm increase. the wife and I are driving out of town at the end of this month and i just wanna make sure we dont get stranded in the middle of the desert.

Thanks in advance.