Adobe Premiere motion settings vs After Effects vs Flash?

  I import a photoshop file,  set the in and out points along with the motion settings in the effects window.  But it seems like whenever I do the play back it flickers/ gets pixelated, or stutters across the screen.  Even when I render the selection and export using different codecs it just dont look right.  Anyone have any suggestions or am I doing something wrong?  Is this something that would work better in ae or an?  What works for you guys?  Please let me know for I am itching to study and learn this.

Thanks.