Wordpress query with multiple variable post IDs

Question

I'm trying to create a custom wordpress query that pulls 3 specific IDs based on 3 different variables that are set using Elliot Condon's brilliant advanced custom fields.

I'm using this to set my variables:

<?php
    $post1 = get_field('post_1');
    $post2 = get_field('post_2');
    $post3 = get_field('post_3');
?>

And I want to pass those variables to a custom query like this:

<?php
    $post_list = array($post1, $post2, $post3);
    foreach( $post_list as $post_id ) :
        query_posts('p='.$post_id);
        while (have_posts()) : the_post();
        // echo the post
        endwhile;
        wp_reset_query();
    endforeach;
?>

However, the above doesn't seem to work and results in a broken page. Anyone have any ideas of how to fix? I'm obviously passing the variables into the query wrong, but I can't figure out how to fix it.

EDIT - SOLUTION

Here's the working updated block. Big thanks to DACrosby! I'm running the query for a custom post type, so I needed to specify which type in the $args.

<div class="row">
    <?php
    $post1 = get_field('related_1');
    $post2 = get_field('related_2');
    $post3 = get_field('related_3');
    $args = array(
        'post__in' => array( $post1, $post2, $post3 ),
        'post_type' => 'work'
    );
    $the_query = new WP_Query( $args );
    ?>
    <?php if ( $the_query->have_posts() ): ?>
    <ul class="case-studies cf fade-in fade-in-3">
        <!-- Basic Projects -->
        <?php while ( $the_query->have_posts() ) : $the_query->the_post(); ?>
            <?php
                //Get Featured Image URL
                $feat_image = wp_get_attachment_url( get_post_thumbnail_id($post->ID) );
                //Get Project Categories
                $terms = get_the_terms( $post->ID, 'type' );
            ?>
            <li class="case-study">
                <img src="<?php echo $feat_image; ?>" alt="<?php the_title(); ?>">
                <a href="<?php the_permalink(); ?>" class="cs-hover">
                    <div class="col-table cs-text">
                        <div class="col-tcell">
                            <span><?php the_title(); ?></span>
                            <span class="divider"></span>
                            <span><?php the_field('description'); ?></span>
                            <?php if(get_field('services')): ?>
                                <ul class="tags">
                                    <?php while(has_sub_field('services')): ?>
                                        <li><?php the_sub_field('service'); ?></li>
                                    <?php endwhile; ?>
                                </ul>
                            <?php endif; ?>
                            <span class="text-link">View Project</span>
                        </div>
                    </div>
                </a>
            </li>
        <?php endwhile; ?>
    </ul>
    <?php endif; ?>
    <?php wp_reset_query(); ?>
</div>

Answer 1

From the documentation

Caveats query_posts() is only one way amongst many to query the database and generate a list of posts. Before deciding to use query_posts(), be sure to understand the drawbacks.

Alters Main Loop query_posts() is meant for altering the main loop. ...

Secondary Loops To create secondary listings (for example, a list of related posts at the bottom of the page, or a list of links in a sidebar widget), try making a new instance of WP_Query or use get_posts().

An example of WP_Query usage:

// The Query
$the_query = new WP_Query( $args );

// The Loop
if ( $the_query->have_posts() ) {
  echo '<ul>';
    while ( $the_query->have_posts() ) {
        $the_query->the_post();
        echo '<li>' . get_the_title() . '</li>';
    }
    echo '</ul>';
} else {
    // no posts found
}
/* Restore original Post Data */
wp_reset_postdata();

From there you'll just modify the $args sent to WP_Query. For example:

$args = array(
         'post__in' => array( $post1, $post2, $post3 ),
         'post_type' => 'desired_post_type'
);