'97 TD AAZ - Weird stumble. Any ideas?

[iggi]

Well..  the jetta and I are back home.
On Sunday I stripped off the belt cover/etc and gave the belt/crank pulley etc a good inspection.  The belt is a bit abused but decently tight.  No wobble or looseness detected on the crank pulley.

So..  I drove it the 750K home.  Mostly at 80-85 kph which made it a long drive but I felt confident that if I babied it there wouldn't be a problem.
I added some ATF to the tank before I headed home and about 3/4's of the way home it was running noticeable smoother.  

My new belt, crank bolt, etc should be here in a couple days and then it's all heading off to my mechanic.  It'll be interesting to see what he say's once it's apart.

[QuickTD]

Everything I have ever read indicates that once the pulley is replaced with another AAZ one, it fails in short order even if there wasn't a problem previously. They all fail eventually

 Mostly true, but there are exceptions. If the pulley has never come loose in the past and there is no play in the keyway, a new pulley and bolt can be installed along with other improvements (one way alternator pulley, new harmonic balancer) and it will survive. I have fixed several of these engines but my own remains stock with 308000km on it.

 That said, if the crank shows any wear once its apart I would highly recommend the TDI pulley fix. It'll seem pretty cheap later when you have to replace the head...

[iggi]

 That said, if the crank shows any wear once its apart I would highly recommend the TDI pulley fix. It'll seem pretty cheap later when you have to replace the head...

Yup.
It all depends on how it looks once it's all apart. Hopefully the crank is good.