air flow meter.
I have no idea how good the rest of your engine is .......
if it's well maintained and in proper tune etc.
but I have had cases of waterboxer engines that 'ran unevenly' ........
and it was from wear on the contacts inside the air flow meter.

'usually' that shows up at more moderate speeds though, say 35 to 40.
At higher speeds, like 70 ..........unevenness gets 'smoothed' out, or so it
seems, due to the higher aerodynamic load - it masks unevenness a little,
but not plane ole loss of power of course.

there's such a thing as 'vanagon syndrome .....and you should have a small
adapter harness on your AFM to prevent that.

If you haven't seen in your fuel filter ........checked for what's in there,
and how restricted it is.........
I'd check into that.  There's usually resistance to checking that since it's
such a messy toxic job,
but it's like working on an electrical problem and never checking the
fuses - a person sure feels dumb going nutty on a problem like that, when it
was a fuse all along. Same is true for the fuel filter or filters - they
need to be mostly decent.

fuel injectors - I sort of 'don't believe' in bad fuel injectors, but of
course after all these years they can be pretty tired.
I just had this case of fuel filter and injector problems on a vanagon.
Original problem was it just would not start on the 3rd day of a camping
trip. A vw shop of some sort ( I wasn't impressed ) got it running, the guy
claims, by 'cleaning the fuel injectors' .   He made the van run, I'll say
that at least.
So I get it, and it's not running right.  ( and he was too lazy or whatever
to check the fuel filter - yet he charged 200 bucks to get it running
....and it sure was NOT anywhere near a full job of repair, not even
slightly-  too typical I fear. )

I did  a spray pattern test on about 10 injectors ......the 4 on the engine
, plus 6 other used ones I have.
On the right side of the engine I found one injector just clogged. I also
found the fuel filter pretty darn restricted.
Checking for a  good spray pattern on those injectors..........I found
several that spray in a dense stream, instead of a nice fine spray, and some
that dripped and leaked.  I put on a new fuel filter of course, and with 4
injectors spraying properly ..........that van is running better than ever
before.
I guestimate  that about 60 % of the vanagon injectors in service that are
over say , 15 years old.........they're only working about 3/4 as well as
they should be.

oxygen sensor output - very easy to check.........
always check that with a digital volt meter, or some device to tell if the
02 sensor is sending the right info to the ECU.

grounds ? ..........always need to know those are good.
plug wires ?
 ...........mostly they work fine, but leaking ones can drive you nuts and
cause subtle problems, or big ones. I have numerous tricks for checking
those, but always consider plug wires too , for running weirdness.

another tip - always check the basics. ( fuel filter is an example )

have fun ! it will be interesting to see what you find.
Scott
www.turbovans.com

----- Original Message -----
From: "Tony Collins" <tonycollin@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Monday, April 13, 2009 12:23 PM
Subject: Faint sputter/stutter at 70mph

> So I had a faint sputter/stutter at 70mph, this happend a couple of times
> ussually when on a headhead wind so I chucked the loss of power to the
> wind.
>
> I had this same thing happen again after a return trip from Ann Arbor, MI
> to
> Detroit Airport on Saturday. As I was pushing 70 and hit the gas the
> engine
> seem to have a flat-lack of power spot. This was marked by decrease in
> speed, all gauges looked good, no lack of electricals or other wierdness.
>
> I do have an exhaust leak, but I did not hear any back fire or the like.
>
> Ideas?
>
> TIA,
> T.
> --
> 82 Scirocco "Rodolfo"
> 85 Vanagon "Blubrik, El Guapo"