Fixin the problem. Its like a game show. If you are really into it there is no finer experience.
So your message here is: There are many reasons for a car to run poorly. Such things as:
-vacuum sensor on top of engine(has 2 vacuum lines coming out of it)
-idle control valve
-etc, etc ....
The "game show" part of your comment is in the exclamation of the solution? That the real test (true technician) is to find the problem quickly and effectively without needless parts replacements?
Got it! I hear you. A lot of the solutions on this board to similiar problems are offered sometimes as universal cure-alls. Unfortuneately, the parts list above could all be contributors to poor running.
I think it was Larry Bible who put it best: Test the basics first. It doesn't matter what you might think its wrong.