It's really just idling rough or kinda stumbling at idle. Vacuum advance seems fine, yeah it moves. When I use the timing light, the ball (timing mark) on the flywheel jumps around in relation to the pointer. It's mostly hitting the mark, but moves a little forward and backward. The truck drives well and seems to be real strong when I cruise and when I hit the accelerator. It just idles rough at stop light and just sitting in the garage. If anybody has any ideas, I'd sure appreciate it. Thanks.
