[wilkin250r]

A gas flow problem sounds unlikely.

It's not impossible, maybe a bad check valve or bad diaphram in the fuel pump that causes it to deliver less fuel than normal, but still pumps some. It may not pump enough at idle, but once you increase the rpms, it pumps more fuel. I suppose it's possible, it's just not likely.

But my first inclination is that it's NOT a fuel delivery problem, because the truck runs and drives fine. The vast majority of fuel problems get worse at higher rpms, not better.

I'm still leaning towards a vacuum leak. There are lots of problems that occur throughout the entire rpm range, the two that only occur at idle are carb idle settings and vacuum leaks. I would concentrate my effort there, first.