Brand new condenser, points, rotor, cap, plug wires, plugs. Old distributor, but it looked fine when I took it apart to clean and test. I suppose I could have gotten a bad condenser. I have another condenser that I could swap in. But I'm confused because it starts right up and then runs so well for a while.
Everything on the engine is either new or rebuilt.
The valves seem to be working well, they might be a little loose, but they go up and down at the right time. No lifters hanging up that I can tell. I am assuming that most settings are pretty close to what they should be, or it wouldn't start so quickly. If I could just keep it running!
With no cab there is no gas pedal, but I have a stiff wire connected to the accelerator pivot and can use that to adjust throttle and keep it in position. I have a cable on the choke, so I can adjust that.
I tightened up the manifold bolts in case there was some sort of leak. I don't think there's a problem there.

Any other ideas?

I am currently digging back in to a 1953 3800 (one ton) with a nine foot bed. I've owned it since 1979, and drove it until 1982 (or so). My wife got me involved in restoring it back in 2002, got the body removed and the frame redone, then things came up. Now I am retired and starting again. If anyone is interested I have photos on Imagur ( https://timwhiteblues.imgur.com/ ). I live way back in the woods in the Ozarks on 40 acres at the end of a 2 1/2 mile private road.

Tim