Quick update. I did an intake cleaning on my TDI last summer at 120,000 miles. I probably should have done it sooner but it is a bit of a messy job. Good News? The TDI intake manifold comes apart so you can really get in there and clean it out. The Bad News? It was full of surprisingly large "diesel boogers", almost walnut sized. I used a cardboard box, gasket scrapers and screwdrivers, parts brushes and brake cleaner to clean it out.
It seems to run much better. There is hardly any soot in the rear view mirror on hard pulls. I am driving faster than in my hard-core hypermiler days and the mpg has not really fallen off. The Golf TDI is a powerful, sporty car that can still return Prius-like mpg.
