Two possibilities - O2 sensor or Vanagon Syndrome. The easy one is to
run it until it happens again, then stop, disconnect  the O2 Sensor and
run it a bit. If the problem doesn't occur again, check your connections
and wiring to the O2 sensor and/or replace the O2 Sensor. If after
disconnected the O2 Sensor the bucking continues to occur, then you
probably have the Vanagon Syndrome. I think if you go through
Vanagon.com you can find a web site with a description on how to deal
with it.

Good Luck.

Regards,

John Rodgers
88 GL Driver

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.
>
>
>