When I press Q and throw the Item, the custom EntityItem goes a random direction rather than the direction the player is facing. Here is my code:

 

package the_fireplace.unlogic.entities;

import java.util.ArrayList;
import java.util.List;

import the_fireplace.unlogic.unbase;
import net.minecraft.block.material.Material;
import net.minecraft.entity.Entity;
import net.minecraft.entity.item.EntityItem;
import net.minecraft.init.Items;
import net.minecraft.item.ItemStack;
import net.minecraft.util.AxisAlignedBB;
import net.minecraft.util.MathHelper;
import net.minecraft.world.World;

public class EntityEnderPearlDust extends EntityItem {
int transformTime = 0;
    /** The health of this EntityItem. (For example, damage for tools) */
    private int health;
public EntityEnderPearlDust(World world){
	super(world);
        this.health = 5;
        this.hoverStart = (float)(Math.random() * Math.PI * 2.0D);
        this.setSize(0.25F, 0.25F);
        this.yOffset = this.height / 2.0F;
        this.delayBeforeCanPickup = 50;
}
public EntityEnderPearlDust(World world, double x,
		double y, double z, ItemStack is) {
	super(world, x, y, z, is);        
        this.setEntityItemStack(is);
        this.lifespan = (is.getItem() == null ? 6000 : is.getItem().getEntityLifespan(is, world));
        this.delayBeforeCanPickup = 50;
}
public EntityEnderPearlDust(World world, double x, double y, double z){
	super(world);
        this.health = 5;
        this.hoverStart = (float)(Math.random() * Math.PI * 2.0D);
        this.setSize(0.25F, 0.25F);
        this.yOffset = this.height / 2.0F;
        this.setPosition(x, y, z);
        this.rotationYaw = (float)(Math.random() * 360.0D);
        this.motionX = (double)((float)(Math.random() * 0.20000000298023224D - 0.10000000149011612D));
        this.motionY = 0.20000000298023224D;
        this.motionZ = (double)((float)(Math.random() * 0.20000000298023224D - 0.10000000149011612D));
        this.delayBeforeCanPickup = 50;
}
@Override
public void onUpdate()
{
	super.onUpdate();
	int j = MathHelper.floor_double( this.posX );
	int i = MathHelper.floor_double( this.posY );
	int k = MathHelper.floor_double( this.posZ );
	transformTime++;
	if ( transformTime > 60 )
	{
		if ( !transform() )
			transformTime = 0;
	}
}
public static boolean isSameItem(ItemStack ol, ItemStack op)
{
	return ol != null && op != null && ol.isItemEqual( op );
}
public boolean transform()
{
	World world = this.worldObj;
	if(!world.isRemote){
	ItemStack item = getEntityItem();
		AxisAlignedBB region = AxisAlignedBB.getBoundingBox( posX - 1, posY - 1, posZ - 1, posX + 1, posY + 1, posZ + 1 );
		List<Entity> l = worldObj.getEntitiesWithinAABBExcludingEntity( this, region );

		EntityItem redstone = null;
		EntityItem glowstone = null;
		EntityItem gold = null;

		for (Entity e : l)
		{
			if ( e instanceof EntityItem && !e.isDead )
			{
				ItemStack other = ((EntityItem) e).getEntityItem();
				if ( other != null && other.stackSize > 0 )
				{
					if ( isSameItem( other, new ItemStack( Items.redstone ) ) )
						redstone = (EntityItem) e;

					if ( isSameItem( other, new ItemStack( Items.glowstone_dust ) ) )
						glowstone = (EntityItem) e;

					if ( isSameItem( other, new ItemStack( Items.gold_ingot ) ) )
						gold = (EntityItem) e;
				}
			}
		}

		if ( redstone != null && glowstone != null )
		{
			getEntityItem().stackSize--;
			redstone.getEntityItem().stackSize--;
			glowstone.getEntityItem().stackSize--;
			if( gold != null ){
				gold.getEntityItem().stackSize--;
				if ( gold.getEntityItem().stackSize <= 0 ){
					gold.setDead();
				}
				worldObj.spawnEntityInWorld( new EntityItem( worldObj, posX, posY, posZ, new ItemStack(unbase.AntiGold)));
			}

			if ( getEntityItem().stackSize <= 0 )
				setDead();

			if ( redstone.getEntityItem().stackSize <= 0 )
				redstone.setDead();

			if ( glowstone.getEntityItem().stackSize <= 0 )
				glowstone.setDead();

			ItemStack Output = new ItemStack(unbase.UnlogicGem, 2);
			worldObj.spawnEntityInWorld( new EntityItem( worldObj, posX, posY, posZ, Output ) );

			return true;
		}}

	return false;
}
}

 

If you need to see any more code, please, let me know

Could it be because you are applying a random velocity to the entity?

 

        this.motionX = (double)((float)(Math.random() * 0.20000000298023224D - 0.10000000149011612D));
        this.motionY = 0.20000000298023224D;
        this.motionZ = (double)((float)(Math.random() * 0.20000000298023224D - 0.10000000149011612D));

Hi

 

Item dropping / throwing takes place in EntityPlayer.func_146097_a(), with motion being set in this bit

                f = 0.3F;
                entityitem.motionX = (double)(-MathHelper.sin(this.rotationYaw / 180.0F * (float)Math.PI) * MathHelper.cos(this.rotationPitch / 180.0F * (float)Math.PI) * f);
                entityitem.motionZ = (double)(MathHelper.cos(this.rotationYaw / 180.0F * (float)Math.PI) * MathHelper.cos(this.rotationPitch / 180.0F * (float)Math.PI) * f);
                entityitem.motionY = (double)(-MathHelper.sin(this.rotationPitch / 180.0F * (float)Math.PI) * f + 0.1F);

 

You could set a breakpoint in there and follow through what is happening, will probably give you a clue.

 

-TGG