Hi,
Here's the story for my '96 850 wagon w/175,000mi:
First,
About 2-3 months ago the car would intermittently run rough or not quite 'catch' at startup. After coughing for 10-20 sec it would 'catch', surge to ~2500rpm, calm down to normal idle and then be fine. This would (and still) happens about 1 in 4 starts with no identified pattern although it may occur more at warmer air temps.

My mechanic/dealer thought it might be a dirty throttle body.

Then,
I thought I could feel a hesitation or bucking at highway speed. Then it became a bit worse and I could see the tach dip so I knew I wasen't imagining it. Just like the startup symptom this one is intermittent.

I THINK it may be the case that a rough startup and hesitation at highway speed occur during the same session. In other words - if it hesitates at startup then it may hesitate at highway speed.

Then,
The check engine light came on.

So,
I went to my mechanic/dealer. They could not duplicate either problem. They say the check engine light was the secondary air pump (I declined the repair) and that the secondary air pump must be replaced prior to continued diagnosis.
They did ofer that it was unlikely that a dirty throttle body could cause both hesitation problems and that it might be an injector.

As the story continues...
I removed, cleaned and reinstalled the throttle body. I've run two techron treatments thru the tank. I've visually inspected hoses and listened for vacuum leaks. The problem continues...

And in conclusion:
I understand from reading other posts that there are quite a few things that may be the culprit here but I haven't seen anyone with these specific symptoms.
Does anyone have any advice or suggestions? They would be much appreciated!
Thanks,
Milt