Runaway Rochester

[DT1]

I've been having a problem with my Q-Jet for some time now. Every once in a while the throttle will stick when I punch it. I thought it was the throttle cable and I figured I'd replace it when I rebuilt the Carb. I just finished rebuilding the engine and yesterday I was in the middle of breaking in the cam when the carburetor ran away on me again. I also rebuilt the carburetor and everything inside and outside looks fine. I disconnected the throttle cable and started it up and gave it a couple of quick jabs and it did it again. I shut it down and started looking for a problem with the linkage. Nothing looked out of the ordinary so I started it up again. It idled like nothing happened. I tried a few times to get it to do it again but it wouldn't. The linkage looks good and I'm pretty sure the throttle plate inside isn't sticking or I could see it from the outside.
Anyone here ever had a similar problem like this? Any suggestions?