My parents have a 2002 Caravan 3.3L with around 185K miles on it currently. The engine has had this problem where when it is first started, it runs rough in a bouncing kind of way but goes away after say 10-15 seconds or after it is revved up a bit. Like all problems like these it is inconsistent. It will do this on cold starts and warm starts, but not all the time. I think it has only stalled once and restarted easily. Nevertheless, my mother has new-car-itis and considering some of the problems I have read about the newer ones and given how Chrysler seems to keep making strides each year on these problems, I would like her to give it one more year to see if the fixes have truly resolved the issues.

They have replaced spark plugs, wires, coils, have sprayed cleaners in the air intake, used fuel injector cleaners, and other typical solutions and none have made any noticable difference.

In some other threads, I have read that short term rough idling could be due to the oil filter. She is having it done at a Ford dealer (since the Chrysler one that used to be in town is gone) and this is one that does NOT have a silicone ADBV. Could a better quality oil filter help resolve this problem? Could maybe switching this over to synthetic oil help?

Any advice would be appreciated.