[kcmarkd]

I had some idle weirdness too, and figured that I had a vacuum leak somewhere. I disconnected all vacuum: distributor, choke pull off, brake booster, etc. Truck stopped wanting to die at idle in gear. Then systematically reconnected each vacuum device and found that when the brake booster was reconnected, the symptom reappeared. I verified that the brake booster was the offending party by trying to pull a vacuum from it. No joy, no vacuum.

Ordered and replaced the brake booster. Now it idles in gear like it used to.