Mine just did that.  Turned out it was a stuck lifter.

Many other causes are possible, I'm sure.

 On 12/13/02 8:19 PM, "James Creech" <jacreech@VISUALLINK.COM> wrote:

> Brothers and Sisters of the List,
> 
> It�s good to be back after about a year away from your wisdom and wit.
> 
> I am having a curious problem � can anyone help?  My 87 Vanagon 2.1
> suddenly lost power in the upper rpms.  It does not buck or lug at all �
> simply fades as I accelerate past about 45 mph.  Starts and idles just
> fine; seems ok at lower speeds, except it won�t top about 3k rpm in any
> gear.  I did find some rust in my gas, but my prefilter seemed to catch
> it and has been replaced, as well as the main fuel filter.  One year ago
> (6k miles) I replaced plugs, wires, distributor cap and rotor, fuel
> lines and pump, fuel pressure regulator, cat, exhaust pipes, O2 sensor,
> temp 2 sensor.  My Digitool readouts all are the same as before this
> problem developed, which would seem to rule out problems in any of the
> components sending info to the ECU.  What should I check?  Fuel
> pressure?  Injector spray pattern and delivery?  Timing?
> 
> TIA,
> Jim Creech
>