Parallax Scrolling from top view (bird view)/ resizing and blank spots

Question

Hello : )
I was thinking this was going to be easy but some problems occurred
Currently Im trying to make a parallax scrolling road while seeing it from above, but there are some issues going on.
the 1st one is that somehow after the second image is gone out of the stage , there are a few blan pixels that are not filled .... and it seems that the speed of the moving is == to the pixels that aren't filled up.
And i think , just asume  that if i test this on like different screen sizes - lets say this is for a phone - ill get some issues with the scaleX and Y and it will get quite ugly and cubic.
I did surch for an example or a tutorial but there are only in a X direction like if you see the car from a side view like this
http://hub.tutsplus.com/tutorials/add-depth-to-your-game-with-parallax-scrolling--active-2 134
the SWF file  si here
http://www.stouchgames.com/APKs/Road.swf
so the current code i have is
package  {
          import flash.display.MovieClip;
          import flash.events.Event;
          public class MainClass_road extends MovieClip {
                    protected var _road:road = new road();
                    protected var _road2:road2 = new road2();
                    public function MainClass_road() {
                              _road.x = stage.stageWidth/2
                              _road.y = stage.stageHeight - _road.height
                              addChild(_road)
                              _road2.x = stage.stageWidth/2
                              _road2.y = y - _road2.height
                              _road2.alpha = 1
                              addChild(_road2)
                              addEventListener(Event.ENTER_FRAME, everyFrame)
                    protected function everyFrame(ev:Event):void{
                              _road.y +=8
                              if(_road.y > 400){
                                        trace("zzzz")
                                        _road.y = y - _road2.height
                              moveBackground2()
                    protected function moveBackground2(){
                              _road2.y +=8
                              if(_road2.y > 400){
                                        _road2.y = y - _road2.height
and the FLA is here
http://www.stouchgames.com/APKs/Road.fla

Answer 1

is there a way to do this only with only as3 code and not by this way :
if the road high graphics are 400 pixels and the stage has 400 height
1.creating the original _road and setting it`s Y to 0
2.go in the same movieClip (of the _road) copy and paste the same graphics but at Y = -400
and then adding the code
               var speed = 4
               var _road:road = new road();
               _road.x = stage.stageWidth/2
                              _road.y = y
                              addChild(_road)
               addEventListener(Event.ENTER_FRAME, everyFrame)
function everyFrame(ev:Event):void{
               _road.y += speed
               if(_road.y > 400 ){
                   trace("zzzz")
                   _road.y = y 
cause it seems (for me )that if i do it with code only - there is a blank spot which amount is the speed in the EveryFrame function
and if no ... can i make it smoother without changing the framerate above 30