allowing all HTML tags in tinymce editor

Try this function from leighton.com :

function override_mce_options($initArray) {
    $opts="*[*]";
    $initArray['valid_elements'] = $opts;
    $initArray['extended_valid_elements'] = $opts;
    return $initArray;
}
add_filter('tiny_mce_before_init', 'override_mce_options');

Hope that helps.