1998 Sierra, 168K, new fuel + air filters, new glow plugs.

Truck idles relatively smoothly, but clatters loudly with gentle acceleration. No black smoke, not stumbling, not stalling. Runs delightfully reliably, starts consistently if not easily.

It's still accelerating relatively smoothly, and the clatter quiets when the turbo kicks in. It gets a consistent 17MPG.

I'm only slightly mechanically inclined, still learning. I'm hesitant to take it to a shop because they'll almost certainly say it's the fuel injector pump, and the issues started 1600 miles ago... Doesn't sound like IP dies slowly for the most part.