Hi SKP,
  What year is your van?

What you describe has some of the features of classic Vanagon syndrome.
 Does your AFM have the "capacitor fix" ?
I don't have time to go into all the details right now, but the archives
have quite a lot of info about this.
  Of course there may be other plausible causes for the problem.

Larry A.

SKP wrote:

>I am hoping someone can shed some light on particularly difficult problem.
>
>When driving on the freeway for a while, I have an abrupt bucking/misfire.
>It is very specific in that it happens only when I slightly let off the
>accelerator and will go away for a few minutes if I press the accelerator
>firmly  or release the accelerator.  Sometimes this behavior will continue
>until I stop the car or may simply stop the behavior on its own.
>
>The only discernable pattern is that if the road requires acceleration and
>deceleration, the problem doesn�t surface.  If there is a steady constant
>speed, and I slightly lift the accelerator, the behavior begins.
>
>
>