Had some time to play with the truck today and found a little nick in one of my vacuum lines. Thought I'd checked them all, but this was down at the bottom of the mikuni carb with two other lines. Amazing how many vacuum lines there are on this thing. Fixed my original stumble problem - YEAH!! Still on my first tank of gas, so I want to make sure any old gas is out of the system before saying for sure. Going to check my plugs and timing next and want to check out the advance as someone else mentioned.

New question: truck doesn't want to start now when it's warm. When I pulled my air cleaner off I could hear some bubbling (truck was hot and had just been driven) and there was a little smoke coming up from the choke side of the carb. Looked like a little witches caldron. I'm pretty sure this isn't normal. Any ideas what this could be? I was about to order a weber carb, but now I've fixed the stumble problem, I'd really like to hold off on that expense for now, especially with having to get the electric fuel pump to go along with it.