Any thoughts on this...need some help!

[quicksilver]

I've been lurking around a while, then got caught up in moving, so I guess you could say this is my first REAL post. Unfortunately, it's a cry for help for the experts I've seen in action here (and everybody else as well) .

I've got a 72 Cheyenne LWB, 3 speed on the column, with a 307 that the guy I bought it from put in it, and it still has a points distributor as well.

I think my problem started back around November when I drove the truck home to Virginia for hunting season. It has just recently gotten noticeably worse, but that may be because I've started a 30 mile/day commute, and the truck is my daily driver. The only way I can describe it is similar to a big gust of wind hitting/slowing the truck down intermittently when I'm pulling a grade, and a little noticeable at higher RPMs before shifting (but not alot). It feels like it just kind of lags or cuts out. Not the engine, but more like maybe clutch or tranny. On level ground it doesn't do it at all except maybe a hint at the higher RPMs, but I try to shift way before that due to my feable attempts to save gas The engine doesn't break up when I'm in neutral and putting some RPMs to it. Which kind of made me think it wasn't fuel or spark. But I've never felt a clutch slip, or had one that was (my best guess) a little over 30 years old. I don't know if he put a new clutch in it, but I doubt it.

If anybody has any thoughts, please feel free to dump them on me. I wasn't sure where to put this thread, so I just thought I'd start it here. Moderators, fell free to move it as applicable. Thanks ahead of time for any help.
'Preciate it.

Doug