240 Hesitation ?

[faof2]

This is a 91 240 station wagon with 110,000 miles , A/C, and auto trans.
I am not sure what to call the phenomenon I am experiencing, so I will describe it.
As I am traveling along, I notice a subtle and extremely brief (a fraction of a second) slowing down of the car, similar to what I experience on a windy day or in a cross wind. I first noticed this about five months ago traveling about 60 mph on the freeway. Then I noticed it when traveling on city streets about 35 mph. Now, I experience it on most trips I take in the car. I have not noticed it when under power or traveling too fast.
My first question is whether this fits the definition of "hesitation", or if this is called something else.
The impression I have is that something is giving faulty input to the computer telling it to do this.
Now I know that there could be be any number of things that I should check.
However, I am hoping that this is a familiar happening that points to one or two things to check.
I ran the on board diagnostics in the fuel injection part of the Bentley manual, and all was normal.
Other than this, the car seems to run fine. Well, the idle is not as smooth as I think it should be.

[240Dad]

Just a guess based on what I have encountered with my 93 240. See if you ever get that quick hesitation with the AC off. I notice that mine will hesitate briefly everytime the AC kicks in.