Figured it out. The Save function is looking for an object, so the dynamically generated Editor name should be encapsulated with the eval function. Fixed code:

 for ( var i=0,n=document.forms[0].elements.length; i<n; i++ )
 {
     var field = document.forms[0].elements[i];
     myString = field.name;
     if (myString.indexOf("_HTMLContent") > 0) {
      myStringSave = myString.slice(0,myString.length-12);
//      alert(myStringSave);
      save(eval(myStringSave));   
  }
 }

Cheers, Kris.