'72 Truck Dying on Incline

[capturedlive]

My '72 GMC Sierra 2500 (402 cu. in.) has recently been giving giving me a pretty hairy problem. At one point on the freeway where there's an incline (and no shoulders) it starts losing power. Punching the gas only makes it worse, and it's only when I release the gas and ease back into it that I have the best luck of getting over the hill. Then, once I'm over and either going downhill or on level road it's fine. However, the other day during rush hour, I completely lost my power and had to stop, put it in Park, and after a couple of attempts, roared the engine back into life and was able to resume (amidst horns and cursing).

I tell mechanics the problem and they scratch their heads. It might be the filter in the gas tank... or it might be the carb... or it might be the points...

Before I take it in, I was hoping this issue might be familiar to someone on the forum. I really don't want to fund a slew of services without a firm resolution.

Thanks.