My '97 850 (106,000 miles) has the tendency to "buck" or "skip" (you can feel the car mildly jerk every few seconds) whenever I am at an idle (stop lights, stop signs) after having driven it for a few minutes. Anybody have any ideas about possible problems and $$ involved?

Earlier I asked about my car's vibration problems/growling on startup. I learned that the problem involved my car being low on fuel, and this was aggravating some sort of secondary fuel pump in my fuel cell. Anyway, after gasing up the problem was gone. Thanks for all the tips.