Steve, looks like the pivot point below your exhaust manifold is pretty rusty / dry. This point siezes up a lot of times and the stud actually starts turning on the threads going in/out of the block as you press the accelerator. Mine had the bad habit of sticking down everyonce in a while requiring that I pull up on the gas button to get it back down to an idle. It was a real butt itch to get it free'd up, but once I got it well lubed and properly adjusted, made a world of difference in driveability.
