Greetings from the road. Currently day 3 of the BABE rally and the first chance I've had to update.
The "mystery stumble" reared its ugly head again and through the day yesterday got progressively worse.
We spent a long time last night and this morning going over everything and can now say the problem is is fixed.
It was the distributor. The shaft had excessive play and was literally tearing into the pickup sensors. Under the dust cap under the rotor it was just a big mess of metal shavings. We were able to find a junkyard in GA with a 91 Capri XR2 so we got another distributor (also has shaft play but not as excessive) and its running great.
Now we have a "wheeeeeeeeee" noise every time the clutch pedal is depressed. I know its probably the throw out bearing, no way we are pulling the trans in a hot parking lot so we are using the clutch sparingly at stops and rev matching the shifts the rest of the way.
If anyone thinks its something beside the throwout bearing I'm open to ideas.
John Muir, the Author of "the idiots guide to VW repair" once noted that he usually started a road trip with a broken down car and ended up with a great one due to all the things they had to repair on the road. I know the feeling.
On the upside this thing just eats up the miles and is a total blast to drive. Need to fix the AC though.