ieatbabies

my car recently started to sputter at idle randomly. some times it does it every 5-10 seconds, sometimes it does it every 60 seconds. i noticed it has a tendency to sputter more after it is warmed up. should be noted that it idles around 650-700 (always has since i picked it up a few months ago) and each sputter does NOT cause rpm to move in any direction. when it stutters i can visually see the engine move, and it causes whole car to "shake". it was throwing codes, as the previous owner told me it might due to cats (gutted). i finally picked up a scanner, and the only codes it showed were p0420 and p0430. since those were the only codes, and the problem has been around for only a few weeks vs the SES light has been on for a few months (i know), im thinking i could rule out my issues due to those codes. the car also seems to be putting out white "smoke" after warmed up and in idle/park. during driving there is no visible trail and it does not stutter once rpms reach over 1200. the car always runs fine under load, but sometimes when taking off it seems like it hesitates a bit (and not every time) till it clears over 1200. the only thing mechanically that has been done to the car was oil change and seafoam in gas tank (2 months ago). during the stutter and sometimes during driving i can feel my exhaust rattling under my feet when it stutters and also occasionally under load. the white "smoke" also seemed to come with the colder weather, as i imagine the minor problem is exacerbated by the cold weather ( i.e. more visible) im not mechanically inclined as i would like to be so this has been confusing to me. from what i read it could be a whole number of things? could a clogged fuel filter cause this? i have yet a chance to change as it has been raining. im lost since the codes it threw seem unrelated and i have no idea where to start... ANY feedback welcome...

ieatbabies

update: after some more internet scouring i came to PCV Valve. it appears to have improved my issue greatly... can still feel it rumble occasionally underneath me, but after it gets a little gas, the rough idle appears to have disappeared but it still seems like its faintly there (could be me trying to find something of nothing) and although it seems to have some white out the tailpipes, its nowhere near what it once was. when removing my PCV valve it was extremely easy to remove and although it wasnt completely clogged, it did have less play than the new one. it went on super easy as well. too easy that when i get around to it, the hoses are getting cleaned and its gonna get a little clamp to insure there are no leaks.