Its that thing in the middle of the pipe that connects the 2 engine pipes to the catalyst with the single wire on it.

Dennis,
From my phone.
________________________________
From: Woody Halsey<mailto:woodyhalsey@GMAIL.COM>
Sent: ‎7/‎15/‎2013 5:50 PM
To: vanagon@GERRY.VANAGON.COM<mailto:vanagon@GERRY.VANAGON.COM>
Subject: Re: engine bucking and bogging - simple answer

Can someone post a link to a photo of the O2 sensor? I have been struggling
with those symptoms forever, been separated from the V'gon for two whole
years, am determined to get it fixed this summer.
Thanks!
Woody Halsey
Woody's Wagen 1983.5

From:  Dennis Haynes <d23haynes57@HOTMAIL.COM>
Reply-To:  Dennis Haynes <d23haynes57@HOTMAIL.COM>
Date:  Monday, July 15, 2013 5:00 PM
To:  <vanagon@GERRY.VANAGON.COM>
Subject:  Re: engine bucking and bogging - simple answer

O2 sensor. Test! When it does that cycle the ignition switch. If it goes
away for a short period O2 sensor or wiring it is. Also, when floored the O2
sensor is ignored.

Dennis,
From my phone.
________________________________
From: Alistair Bell<mailto:albell@SHAW.CA>
Sent: ?7/?15/?2013 3:59 PM
To: vanagon@GERRY.VANAGON.COM<mailto:vanagon@GERRY.VANAGON.COM>
Subject: engine bucking and bogging - simple answer

Another minor story.

August 2010, 6 day trip into fairly remote logging roads on west coast of
Vancouver Island. Van running fine until one day, mid day, it starts bogging
and missing and stalling. I spent a couple of hours looking at the engine
(wasn't a heck of a lot I could do out there). We could still drive, the
problem would come and go with no rhyme or reason. We made it to Nitinat
village and filled up with gas. Problem didn't come back. Oh BTW, I had
replaced the fuel filter the month prior to trip.

A year later, 2011, in the interior of BC (Cariboo area, travelling east
down to Little Fort to then go down to Kamloops) the same thing happened.
Exactly the same symptoms. Problem disappeared after next gas fill up.

No problems in 2012.

And now, weekend before last, same thing happened. Logging road travel, warm
day, about 1/2 tank gas. I fiddled with engine again, nothing obviously
wrong. We could make it back home, the problem was on and off. When it did
buck and bog, I found that flooring it would make engine run normally. Next
day the problem was still there. I took off TB and adjusted throttle switch.
I added 250 ml of isopropanol to gas tank. Problem went away, mostly. Just
the occasional hiccup. Filled up with gas, no problems since.

I'm really suspecting bad gas, ie water in gas tank. I can't think of any
other reasons.

alistair