Speed keeps stacking in actionscript 3.0 - actionscript-3

Question

We have been making this game for our class CPT and you play as a character and try to get through these levels but the issue is that every time you die and go back to play the level again the speed stacks on top of the previous speed to a point where the game isn't even playable anymore. We have tried resetting it and setting it back to 0 but nothing seems to work we also tried to code it so that is the speed goes past 21 it resets back to 20 (our ideal speed) we also tried to remove extra event listeners that could have been stacking on top of the other. and if you do happen to die but get to the next frame the speed goes back to 20 for that frame.But if you die on that frame it doubles the speed on that frame too.Our code is:
import flash.events.Event;
import flash.display.MovieClip;
//makes the character jump
var grav:Number = 10;
var jumping:Boolean = false;
var jumpPow:Number = 0;
stage.addEventListener(KeyboardEvent.KEY_DOWN, whenKeyPressed);
stage.addEventListener(Event.ENTER_FRAME, update);
function whenKeyPressed(event:KeyboardEvent):void
{
if(event.keyCode == Keyboard.UP)
{
if(jumping != true)
{
jumpPow = -50;
jumping = true;
}
}
}
function update(event:Event):void
{
if(jumping)
{
player_mc.y += jumpPow;
jumpPow += grav;
if(player_mc.y >= stage.stageHeight)
{
jumping = false;
player_mc.y = stage.stageHeight;
}
}
//when the character makes it to the other side of the screen, the frame
changes
if (player_mc.hitTestObject(frameChanger1))
{
gotoAndStop(91);
}
//end the game when the character touches the penguin
if (player_mc.hitTestObject(penguin1))
{
gotoAndStop(89);
}
}
//makes the character move left and right
var leftPressed:Boolean = false;
var rightPressed:Boolean = false;
player_mc.addEventListener(Event.ENTER_FRAME, moveInDirectionOfKey);
stage.addEventListener(KeyboardEvent.KEY_DOWN, setKeyPressed);
stage.addEventListener(KeyboardEvent.KEY_UP, unsetKeyPressed);
function moveInDirectionOfKey(event:Event)
{
if (leftPressed)
{
player_mc.x -= 20;
}
if (rightPressed)
{
player_mc.x += 20;
}
}
function setKeyPressed(event:KeyboardEvent):void
{
switch (event.keyCode)
{
case Keyboard.LEFT:
{
leftPressed = true;
break;
}
case Keyboard.RIGHT:
{
rightPressed = true;
break;
}
}
}
function unsetKeyPressed(event:KeyboardEvent):void
{
switch (event.keyCode)
{
case Keyboard.LEFT:
{
leftPressed = false;
break;
}
case Keyboard.RIGHT:
{
rightPressed = false;
break;
}
}
//when the character makes it to the other side of the screen, the frame
changes
if (player_mc.hitTestObject(frameChanger1))
{
gotoAndStop(91);
}
//end the game when the character touches the penguin
if (player_mc.hitTestObject(penguin1))
{
gotoAndStop(89);
}
}

Answer 1

Did You tried :
if(!stage.hasEventListener(Event.ENTER_FRAME)){
stage.addEventListener(Event.ENTER_FRAME, update);
}
if(!stage.hasEventListener(KeyboardEvent.KEY_DOWN)){
stage.addEventListener(KeyboardEvent.KEY_DOWN, setKeyPressed);
}
if(!stage.hasEventListener(KeyboardEvent.KEY_UP)){
stage.addEventListener(KeyboardEvent.KEY_UP, unsetKeyPressed);
}
if(!player_mc.hasEventListener(Event.ENTER_FRAME)){
player_mc.addEventListener(Event.ENTER_FRAME, moveInDirectionOfKey);
}
And so on...
Otherwise You will register the Events multiple times...
This may be the issue.
I'm not sure, I avoid to code on multiple frames.
You may also use the answer of #Philarmon here Function being called faster