air flow meter is a good candidate.
timing should at least be in the ball park of correct.  Too advanced
initially isn't good.

but the old sensors back in !
Scott

----- Original Message -----
From: "Robert Stewart" <robertmstewart@MAC.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Saturday, August 08, 2009 11:39 AM
Subject: 1988 Rebuilt Engine Stumbling at various RPM levels 2100-2300,
3400- 4000rpms

>I just got my Rebuilt Engine back in my automatic 88 wolfsburg. It's
> been Stumbling at various RPM levels between 2100-2300rpm & 3400- 4000
> rpm's.
>
> It has good power through the band but if you are not pushing the
> accelerator down and staying steady at any of the RPM ranges stated
> above it will stumble once in a while, not continuously.
>
> The engine only has 100 miles on it so far. Mostly country road
> driving with very little highway driving.
>
> It has a brand new bosch O2 sensor, all other sensors on the van are
> new.
>
> New Fuel Lines, Injectors are 2 yrs old. New fuel in the tank, all old
> fuel in the tank was removed. All new fuel lines on the tank as well.
> New Oil filter and Fuel Filter. Air Cleaner just cleaned.
>
> Any ideas of what I should be looking for?
>
> Could it be the advance timing on the engine?
> Maybe it was set incorrectly?
>
> AFM problem?
>
> Thanks,
> Robert
> NY