I've seen this before too...I had a Syncro that would just sputter start then die.

Ben (of Montreal) and myself played around swapping pretty much every ignition component then he realized even though we had spark and fuel, the engine could not exhale.  Engine gotta breath in order to run!

After we pulled the Cat we could see it was plugged up with broken cat guts.   Installed a new cat, van has been fine ever since.

>I made a new friend this week on the Samba. He posted about a vexing
>problem with his son's recently acquired 87 Wolfsburg. It had just died
>as he was driving and then would not start. He had it towed home and was
>trying to get it going. A former VW mechanic friend came over with tools