If o2 sensor, you can run without.  Fuel economy will suffer dramatically. 

Karl Wolz
Sent from my electronic umbilicus

On Apr 8, 2012, at 6:36 AM, Dennis Haynes <d23haynes57@HOTMAIL.COM> wrote:

> O2 sensor, Temp 2 sensor, airflow meter or major vacuum leak. The archives
> have a lot of good information.
> During the power loss try resting the ignition, (quickly turning key off and
> then back on). If power resumes for a short period you have an O2 sensor or
> wiring issue.
> 
> Dennis
> 
> 
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> Liberte, Joel
> Sent: Saturday, April 07, 2012 11:19 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: 90 Syncro engine power probs
> 
> Greetings, and sure wish I was drifting on the outskirts of the pdl for a
> while before I had problems.
> 
> Newbie to the group and the VW world, just picked up my '90 Syncro with
> original 2.1 and am having problems, just before I drive 1500 miles home.
> 
> Started when driving just outside of Denver in the mountains, in 4th gear
> there was basically no power to the engine at all, rpm at idle no matter
> where the gas.  Dropped to 3rd and was able to keep up the speed with a bit
> of higher rpm.  (yes, am aware of the hills and the lack of hp so fully
> expected it to be a wee bit slower).  I needed to down shift again due to
> the grade and after a couple minutes, the power in 2nd dropped to almost
> zero, same in 1st as well at this point.  I was off to the side barely
> moving, this went on for about 5 miles when it went back to a normal rpm and
> picked up speed.
> 
> Did it again today in all the gears, no more than idle rpm no matter where
> the gas pedal.  Did check the linkage between the peddle and the engine and
> no problems there.
> 
> 1500 miles at about 2 miles per hour, should be home by summer 2023.
> 
> Thanks for any ideas and suggestions.  Happy to have joined but sure would
> have liked it in a different fashion.
> 
> Joel L