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