I need help with a vibration issue i've had ever since i changed out old motor and trans . all hardware seems to be tight but taking off and when sec. throttle plates are accuated it shakes and vibrates.

 

So it happens when engaging the clutch, right as you get going? I don't see how you know the secondary throttle plates are open, since you can't see them while you're driving. Is this your way of saying you're mashing the throttle pedal?

Based on your limited info, I'd guess it could be a flywheel that didn't get resurfaced, or bad motor/trans mounts.