My girlfriend's bucking problem...need help with her 4000

[Holman, Scott]

My girlfriend has a 1985 4000S Quattro with approx 140,000 miles.

For the past few winters, the car has developed what by girlfriend calls a =
"bucking problem".  It typically occurs when starting out from a stop, but =
has recently occurred at highway speeds.

Rather than me try to explain it, I've asked her to describe the problem in=
 her own words:

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Well...I'm not too sure what all has been replaced, though I know there was=
 some fuel line work done and I believe a fuel pump has been replaced, not =
sure if it's the primary or secondary...which ever is cheaper.  The last ti=
me when i was underneath it looking in that general area, i noticed somethi=
ng labeled in the factory repair manual as the "accumulator" looked to be o=
riginal...all rusty and gross looking.

Every once in a while, she will buck in first gear when I start out...somet=
imes so lurching-like that it actually hurts my neck and makes it hard to k=
eep my foot on the accelerator to pull out in an intersection.  I usually j=
ust let off the gas and try it again.

Tuesday on my way home, I was in 5th gear going about 70mph and she started=
 bucking while I was going.  I was not in cruise control, and my foot was o=
n the accelerator.  I immediately let off the gas and downshifted to fourth=
. I left my foot off the accelerator and my gear shift began flobbling in m=
y hand like crazy with the bucks.  When I came to a stop, i pulled out ok w=
ith no bucks, but by third gear she was bucking again and the gear shift wa=
s flobbling in my hand again.  I thought the tranny was coming lose and was
going to fall out. the weather was fine, around 55 degrees, and no rain. I =
let her sit for a day and last night and this morning, she was fine.
------------------------------------

Let me know what you guys think.  Her car will be in the shop next week for=
 some minor suspension work, so I'd like to order any parts relatively soon=
.

Thanks,
Scott Holman
www.audi12v.com (my car!)