My 2001 SEL has a problem idling when in drive, sitting at a stoplight at a stop. the idle is bumpy, meaning it idles but it will feel as if somthing is bumping in there. Not a regular interval, just once, then a few times the once or twice. irregular, but is doesn't go away. Something like that. Hot of cold, makes no difference.The 'bump' is reflected in the tachometer. If I take it out of drive, ie: park or neutral, it idles fine. No check engine light. Is this a warning of fun times to come with the mechanic? THANKS in advance!