Ok, here's the problem. My engine runs nice and smooth till I put the truck in gear. Once in gear, it has a shimmy which vibrates the whole truck. I fixed all the vacuum leaks and the shakes got better but it still bounces around. I also replaced the plugs, and checked the wires. I even bumped the timing up a little and it's still there. Like I said earlier, it only does this when idling in gear, if it's in park or neutral then no shake. Please let me know what I can check out next.