[dmjlambert]

Today I was just driving along a road at 45 MPH, and it had a tantrum. It ran poorly and just struggled and almost died for about 10 seconds. Then it went back to running excellent for the rest of my trip. Where exactly is the corner of the Bermuda Triangle today? Maybe I'm running through it.
Before my trip I connected an analog voltmeter to fuse panel at the unfused ignition terminal, so I can monitor my voltage just for the heck of it. It ran steady at about 15 volts the whole time, including during the tantrum. I'm still poking around trying things. Coley, I will probably take your suggesting of having a close look at the carburetor, one of the next steps.

davepl I have added the fuel line to the suspect list, but I think it is a long shot. I have pretty new 3/8 rubber hose in the stock locations and it is in good shape and feels firm. Both lengths of it are before the mechanical fuel pump. They are stock length of about 8 to 12 inches long to make the distance from the frame to the section of metal tubing that goes up into the cab, and from the frame to the mechanical fuel pump inlet. The sections of hose should have pretty much no serious suction going on with them, just gravity fed fuel going into the low-pressure fuel pump. It is not a performance engine, just a plain old stock setup and I'm driving like a granny. Also, the fuel cap is vented and I never hear or feel a suction or pressure release when removing the cap to refuel.

Thank you everybody for your comments.